■ CANADA Daylight Saving Time Begins

[Mundy]

2017년 디스커버리 패스(Discovery Pass) 무료 제공

Canada 건국 150주년을 맞이해 캐나다에서 진행되는 다채로운 행사중에 건국이래 처음 시행하는 통근 선물이 포함되어 있습니다

​Canada 연방정부 환경부 소속인 국립공원 관리국[PARKS CANADA(http://www.pc.gc.ca/en/index)]산하의 모든 입장료를 2017년 한해 동안 면제해 준다는 내용입니다.

46개의 국립공원 뿐 아니라 ​171개의 역사유적지, 해양 보존 지역 등 국립공원 관리국에서 운영하는

모든 곳을 무료로 방문할 수 있습니다

2017년 캐나다 여행을 계획하고 있다면 국립공원을 무료로 입장할 수 있는 패스를 미리 신청하세요.

개인당 신청는것이 아니라 차량 1대당 1개의 패스가 필요합니다

무료로 제공되는 디스커버리 패스(Discovery Pass)는 2017년 한 해 동안만 유효합니다

http://www.pc.gc.ca/eng/voyage-travel/admission.aspx

​위 링크를 누르시면 국립공원을 무료로 입장할 수 있는 디스커버리 패스 신청 사이트로 연결됩니다.

대수롭지 않게 생각 할수도 있겠지만 Canada는 연간 입장료 수입만으로도 $60억 정도를 넘어섭니다

PARKS CANADA 입장에서는 엄청난 수익을 포기하고 방문자들에게 혜택을 주는 것입니다

2016년 디스커버리 패스는 $136.4 에 판매되었습니다

■ 2017년 3월 12일(음력 2월 15일) CANADA Daylight Saving Time Begins(3월 두번째 일요일)

시작하는 날 : 2017년 3월 12일(3월 두번째주 일요일) 02:00를  → 03:00로

12일 오전 2시를 오전 3시로

12일 오전 2시를 오전 3시로, 일광시간절약제 실시

문용준 기자 myj@vanchosun.com 기자의 다른 기사보기

                

“한 시간 손해, 시차 변화에 잘 적응해야”

12일 오전 2시를 기점으로 흔히 써머타임으로 알려진 “일광 시간 절약제”(Daylight Savings Time: DST)가 시작된다. 이에 따라 당일 오전 2시는 오전 3시로 조정돼야 한다.

DST는 낮 시간대 활동을 늘려 밤에 쓰여지는 에너지를 아껴보자는 취지에서 도입됐다. 하지만 그 효과가 미미하다는 것이 일부의 주장이다. 관련 부작용도 무시할 수 없다. DST 적용 후 한동안은 시차 문제가 불거져 나오기 때문이다. IDST 실시 후 첫 월요일에 발생한 교통사고 발생 건수가 그 전주 동일에 비해 7% 증가한다는 ICBC(BC 차량보험공사)의 통계도 있다. 

짧아진 낮 시간으로 인해 퇴근길 운전이 힘들어진다는 게 그간의 경험담이다. 관련 피해를 줄이기 위해서는 운전 시 제한 속도를 준수하고 시간적 여유를 갖는 등의 노력이 필요하다.

한편 일광 시간 절약제 적용 이후 한국과의 시차는 기존 17시간에서 16시간으로 한 시간 줄어든다. 밴쿠버 시각에서 4시간을 더한 뒤 밤과 낮을 바꾸면 한국 시각이다.

문용준 기자 myj@vanchosun.com

Canada, Mexico and the United States[edit]

Main articles: Daylight saving time in Canada, Daylight saving time in Mexico, and Daylight saving time in the United States

Canada, Mexico and the United States use Daylight saving time on a wide scale, with only a few states/provinces and parts thereof opting out of the practice or adopting it year-round without the twice yearly switch.

The United States territory of Puerto Rico adopted DST through legislation passed in 2000 but, after a change in governors, dropped it in 2001, three days before it would have gone into effect.

Since 2007, in areas of Canada and United States in which it is used, daylight saving time begins on the second Sunday of March and ends on the first Sunday of November. In Mexico, Congress has consistently been refusing to adopt this schedule on a nationwide basis for nearly a decade. Therefore, only certain border cities in Mexican states that observe DST follow the same pattern as Canada and the United States. The rest of Mexico remains out of phase beginning DST on the first Sunday of April and ending on the last Sunday of October, the same schedule followed by Canada and the United States prior to 2007.

일광 절약 시간제(日光節約時間制, 미국 영어: Daylight saving time, DST) 또는 서머 타임(영국 영어: summer time)은 하절기에 표준시를 원래 시간보다 한 시간 앞당긴 시간을 쓰는 것을 말한다. 즉, 0시에 일광 절약 시간제를 실시하면 1시로 시간을 조정해야 하는 것이다. 실제 낮 시간과 사람들이 활동하는 낮 시간 사이의 격차를 줄이기 위해 사용한다. 여름에는 일조 시간이 길므로 활동을 보다 일찍 시작하여 저녁 때 직장이나 학교에서 이렇게 '절약된 낮 시간'을 더 밝은 상태에서 오후에 활동할 수 있게 하는 효과가 있으며, 또한 직장이나 학교에서의 조명과 연료 등의 절감 효과를 기대할 수 있기 때문이다. 온대 지역에서는 계절에 따른 일조량의 차이가 크므로 일광 절약 시간제는 보통 온대 지역에서 시행된다.

여러 정부는 일광 절약 시간제를 특히 낮시간의 효율적인 사용을 통한 에너지 절약의 효과를 앞세우며 홍보한다. '깨어 있는 시간'을 조절함으로써 전기 조명의 사용을 절약할 수 있다는 것이다. 하지만 일광절약시간제를 반대하는 사람들은 이 주장이 근거가 없다고 반박한다. 소위 "일광절약" 기간 동안 냉방수요를 증가시켜 전반적으로 에너지를 낭비하도록 하기 때문이다.^[1] (에너지 사용에 대한 영향 참조.)

일광절약 시간제는 수면시간을 연중 두 차례나 인위적으로 조정하기 때문에, 교통사고 및 사망 증가, 수면의 질 및 건강의 악화, 인지능력 훼손 및 업무생산성 저하 등 인간행동에 부정적인 영향을 미친다. ^[2] (인간행동에 대한 영향 참조.)

일광 절약 시간제는 통상 봄에서 가을까지(3월 중순 ~ 11월 초) 계속되므로 서머 타임의 '서머'(여름)라는 말에는 어폐가 있으나, 영국을 비롯한 유럽 지역에서는 서머 타임이란 말을 더 많이 사용한다.

목차

 [숨기기] 

• 1 역사
• 2 한반도의 일광 절약 시간제
• 3 남반구의 일광 절약 시간제
• 4 유럽의 일광 절약 시간제
• 5 미국과 캐나다
• 6 폐지된 나라
• 7 에너지 사용에 대한 영향
• 8 인간행동에 대한 영향
  • 8.1 수면
  • 8.2 교통사고
  • 8.3 사망
  • 8.4 건강
  • 8.5 인지능력
  • 8.6 업무생산성
• 9 기타 비판
• 10 각주
• 11 바깥 고리

역사[편집]

1784년 미국의 벤저민 프랭클린은 여름에 더 일찍 일어남으로써 보다 경제적으로 오전 시간을 이용할 수 있으며, 따라서 밤에는 더 적은 양의 초가 소모될 것이라는 발상을 내었다. 하지만 벤자민 프랭클린은 시계를 조절하자고 주장한 것은 아니었다. 최초로 일광절약시간의 개념이 등장한 것은 1905년에 윌리엄 윌렛에 의해서였다. 그는 야외 활동을 무척 좋아하던 건설업자였는데, 이러한 발상으로 보다 효율적으로 골프를 즐길 수 있을 것이라고 생각했다. 2년 뒤에 그는 이 발상을 출판하고, 발포어와 처칠, 로이드 조지, 에드워드 7세 등의 지원을 받을 수 있었다. 하지만 당시 수상이던 아스퀴스는 반대하였다. 이후 윌렛과 그의 동지들은 1911년부터 1914년까지 계속 이 안건을 상정하였다. 제1차 세계 대전 중에 일광절약시간은 전쟁 중에 연료를 절약하고 공습을 대비하기 위한 목적으로 이용되었다. 한편 영국의 적이었던 독일도 이 발상을 받아들여 유럽 최초로 1916년 4월 30일부터 실시하였다. 영국은 1916년 5월 21일에 처음 실시하였으며, 러시아와 다른 유럽 국가들은 이듬해에 잇따라 시행했다. 오스트레일리아와 캐나다도 따르려 했으나 이들 지역의 농부들에게 이 생각은 그다지 인기가 없었다. 또한 전쟁이 끝나자 많은 나라들이 일광절약시간을 폐지하였다. 미국은 1918년 3월의 마지막 일요일부터 10월의 마지막 일요일까지 일광 절약 시간을 실시하였으나, 1919년 이후에는 의회에서 이를 폐지하였다. 이후 또 한 명의 골프광이었던 우드로 윌슨 대통령이 다시 실시하게 하였다.

한반도의 일광 절약 시간제[편집]

대한민국에서는 1948년~1951년, 1955년~1960년, 1987년~1988년에 일광 절약 시간제가 실시되었다. 반면, 조선민주주의인민공화국에서는 일광 절약 시간제가 시행된 적이 없다.

대한민국에서는 1955년~1960년의 기간에 표준시의 기준 자오선이 동경 127° 30분으로 현재보다 30분 늦은 시간대를 썼기 때문에, 서머 타임 실시 중에는 현재보다 30분을 앞당긴 셈이었다. 1987년과 1988년의 서머 타임은 서울 올림픽 TV중계를 위해 실시한 제도로, 시민들의 생활 리듬을 깨고 혼란만 야기시킨다는 비난 여론이 빗발쳐^[3][4] 올림픽이 끝난 후에는 시행되지 않았다.

2009년 이명박 대통령 직속 녹색성장위원회에서 일광절약시간제 도입을 추진하기도 했으나,^[5][6] 대한민국은 동경 135° 기준인 UTC+09를 쓰기 때문에 이미 연중 30분 가량 일광절약시간제가 시행되는 효과가 있다는 반론과 함께, 생활의 불편과 혼란만 야기한다는 반대 여론이 많아 시행되지 않았다.

대한민국의 일광 절약 시간제 실시 시기

1948.06.01. 00:00 ~ 1948.09.13. 00:00

1949.04.03. 00:00 ~ 1949.09.11. 00:00

1950.04.01. 00:00 ~ 1950.09.10. 00:00

1951.05.06. 00:00 ~ 1951.09.09. 00:00

1955.05.05. 00:00 ~ 1955.09.09. 00:00

1956.05.20. 00:00 ~ 1956.09.30. 00:00

1957.05.05. 00:00 ~ 1957.09.22. 00:00

1958.05.04. 00:00 ~ 1958.09.21. 00:00

1959.05.03. 00:00 ~ 1959.09.20. 00:00

1960.05.01. 00:00 ~ 1960.09.18. 00:00

1987.05.10. 02:00 ~ 1987.10.11. 03:00

1988.05.08. 02:00 ~ 1988.10.09. 03:00

남반구의 일광 절약 시간제[편집]

남반구는 북반구 지역의 겨울 동안에 일광 절약 시간제를 시행한다. 호주는 10월의 첫 일요일 오전 2시에 시작하여 다음해 4월의 첫 일요일 오전 3시에 해제한다. 시행 지역은 뉴사우스웨일스 주(NSW), 빅토리아 주(VIC), 사우스 오스트레일리아 주(SA), 테즈메이니아 주(TAS), 오스트레일리아 수도 준주(ACT) 이다.^[7] 뉴질랜드는 10월의 첫 일요일 오전 2시에 시작하여 다음해 3월 세 번째 일요일 오전 3시에 해제한다. 브라질은 10월의 세 번째 일요일 오전 12시에 시작하여 이듬해 2월의 세 번째 일요일 오전 12시에 해제한다.

유럽의 일광 절약 시간제[편집]

중부 유럽지역은 3월 마지막 일요일 1시(GMT 기준)에 시작하여 10월 마지막 일요일 1시에 해제된다. 그렇게 되면 대한민국과 영국,포르투갈,아일랜드의 시간차는 8시간으로, 독일,프랑스,이탈리아,스페인 등 대륙 주요국은 7시간으로 줄어든다. 핀란드,불가리아,그리스 등과는 시차가 6시간이 된다.

미국과 캐나다[편집]

미국과 캐나다는 2006년까지 각 시간대의 지역시간 기준으로 4월의 첫 일요일 오전 2시에 시작하여 각 시간대의 지역 시간 기준으로 10월의 마지막 일요일 오전 2시에 해제하였으나, CST 지역은적용되지 않는다. 미국과 캐나다는 2007년부터 일광절약시간제 기간이 늘어나 각 시간대의 지역 시간 기준으로 3월의 두 번째 일요일의 오전 2시에 시작하여 각 시간대의 지역 시간 기준으로 11월 첫 일요일 오전 2시에 해제하도록 바뀌었다. 유럽은 동시에 일괄적으로 바뀌는 데 비해 미국은 시간대 별로 바뀌는 시간이 잇달아 일어나는 것이 특징이다. 이러한 변경은 43대 미국의 대통령인 조지 W. 부시 대통령이 2005년에 서명한 에너지 정책법(2005년 8월 8일)에 따른 것이다.^[8]

미국과 캐나다에서 이러한 일광 절약 시간제를 따르지 않는 지역도 있다. 하와이 주, 미국령 사모아, 괌, 푸에르토리코, 버진 아일랜드, 애리조나 주, 인디애나 주와 캐나다의 서스캐처원 주 등이 그러하다. 그러나 애리조나 주 지역에서 나바호족 자치지역은 일광절약시간제를 따르기도 한다. 또한 일광 절약 시간제 때문에 시간을 바꾸어야 하는 미국 사람들에게, 소방서에서는 이때 화재 경보기의 배터리를 교환할 것을 권유하는 시기로 활용하고 있다.

폐지된 나라[편집]

이집트는 4월의 마지막 금요일 낮 12시에 시작되어 9월의 마지막 금요일 낮 12시에 해제하였다. 그러나 2011년 4월부터 일광 절약 시간제를 폐지하기로 합의했다.^[9] 따라서 이 이후부터 대한민국과 이집트의 시차는 7시간으로 고정된다.

러시아는 UTC로 3월의 마지막 일요일 오전 2시에 시작하여 10월의 마지막 일요일 오전 3시에 해제한다. 하지만 러시아 역시 2011년 3월에 일광 절약 시간제를 적용한 후 이를 해제하지 않기로 합의했다.^[10] 따라서 대한민국과 러시아 모스크바의 시차는 6시간으로 고정되었다. 같은 논의가 벨라루스에서도 이루어져 같은 해에 폐지되었다.

이라크는 4월의 첫 번째 토요일 오전 3시에 시작하여 10월의 첫 번째 일요일 오전 4시에 해제한다. 그러나 이 역시도 2007년 이후로 폐지되었다.

이 외에도 많은 나라들이 21세기 이후로 폐지하여 2013년 기준으로 유럽과 북미, 중동 일부 국가와 남반구 일부 지역에서만 실시되고 있다.

에너지 사용에 대한 영향[편집]

일광절약제는 냉난방수요를 유발해 전기사용량을 증가시킨다. 학술지 "경제와 통계 논평(The review of economics and statistics)” 2011년 93권 4호에 실린 논문 "일광절약제도는 에너지를 절약할까? 인디애나의 자연적 실험을 통한 근거(Does daylight saving time save energy? Evidence from a natural experiment in Indiana)”에 따르면, 4-10월사이에 전기사용량이 더 많다. 전반적으로 0.98%를 더 사용한다. 일광절약제가 실시되는 기간 냉방으로 인한 전기 수요가 증가하기 때문이다.^[11][12]

인간행동에 대한 영향[편집]

학술지 수면의학평론(Sleep medicine reviews)에 실린 논문 "일광절약제가 수면과 인간행동에 미치는 영향(The impact of daylight saving time on sleep and related behaviors)"은 일광절약제 시행의 영향을 과학적으로 탐구한 연구논문 약 60편을 분석해, 일광절약제가 수면, 교통사고, 사망, 건강, 인지능력, 및 업무생산성 등에 미치는 영향을 한 종합적으로 제시했다.^[13]

수면[편집]

• 시간을 당기는 봄철에는 DST시행후 한 달 간 수면시간이 40분 정도 감소하나, 원상복귀하는 가을에는 수면시간 변화 없음.
• 아침형은 봄철 시간조정에 적응을 잘하는 편이나, 저녁형은 수면의 질이 크게 나빠짐.
• 새롭게 설정된 기상 시간에 적응하는 기간은 5일 정도 소요.

교통사고[편집]

• 봄철 시간조정 이후 약 2주 동안 대체로 교통사고 발생 7-10% 증가. 다만, 스웨덴 핀란드 등 북구에 위치한 지역에서 실시한 연구에서는 봄철에도 교통사고 증가가 관측되지 않았음. 해가 늦게 뜨는 북구지역은 봄철 시간조정으로 출근시간을 한시간 당겨도 도로의 상황변화가 크지 않았기 때문인 것으로 추론 가능.
• 가을철 시간조정 이후에는 교통사고 발생 변화 없음.

사망[편집]

• 봄철 시간조정 이후 일주일간 사망률 6.5% 증가. 가을철 시간조정이후에는 사망률에 변화 없음.

건강[편집]

• 급성심근경색과 뇌졸증 발생 증가
• 자살율에 대해서는 연구결과가 일치하지 않음. 일광절약제 시행과 자살시도와의 상관성을 찾은 연구도 있지만, 상관성을 찾지 못한 연구도 있음.

인지능력[편집]

• 인디애나주에서는 2006년 이전에는 21%의 지역에서 일광절약시간제를 시행했으나, 2006년 주내의 모든 지역에서 실시하도록 강제했음. 따라서 인디애나 주는 자연스럽게 비슷한 지역의 비슷한 사람을 대상으로 일광절약시간제의 영향을 비교할 수 있는 상황이 조성. 인디애나주 350개 고등학교의 SAT(Scholastic Assessment Test)점수 10년치를 비교한 결과, 일광절약시간제를 시행한 지역 고등학교의 성적이 유의미하게 낮았음. 이는 수면리듬의 혼란이 인지능력을 손상시킬 수 있다는 견해를 뒷받침 ^[14].

업무생산성[편집]

• 봄철 시간조정 이후 근무시간에 딴짓하는 시간 증가. 봄철 시간조정 직후 월요일의 인터넷 검색기록을 시간조정 직전의 월요일의 검색기록과 비교했을 때, 일과 관련이 없는 오락과 관련된 내용 검색이 유의미하게 많았음. 논문 저자는 이를 수면시간 감소에 따른 자아조절 능력의 상실로 해석 ^[15].

기타 비판[편집]

이외에도 일광절약시간제는 다음과 같은 이유로 비판받고 있다.

1. 전 세계의 컴퓨터 시간을 바꾸는 데 엄청난 시간을 소모하고 혼란을 일으킨다. 이는 실시하고 있지 않은 지역에서도 마찬가지로 발생하며, 전 세계 수많은 컴퓨터의 작동 시간이 이에 소요되고 있으며, 국제 간 연락에도 영향을 미치고 있다.
2. 여러 시간대(특히 일광절약시간제를 쓰지 않는 시간대와 쓰는 시간대)를 오가는 사람들에게 혼란을 일으킬 수 있다.
3. 해마다 두 차례씩 시간을 맞추어야 하니 번거롭다.
4. 일광 절약 시간제는 전 세계적으로 쓰이지 않는다.
5. 한 시간이 중복되는 경우가 생긴다.
6. 학생과 직장인은 일광절약시간제의 시작과 끝에는 해가 뜨지도 않았는데 등교/출근해야 하는 경우가 생긴다.
7. 농부들은 시간에 관계 없이 해가 뜨면 일어나야 한다. 그리고 젖소의 젖이 나오는 때는 시계가 가리키는 시간에 관계없이 일정하다.

각주[편집]

1. 이동 ↑ Kotchen, Matthew; Grant, Laura (2011). “Does Daylight Saving Time Save Energy? Evidence from a Natural Experiment in Indiana”. 《The Review of Economics and Statistics》 93 (4): 1172-1185. 2015년 12월 13일에 확인함. 
2. 이동 ↑ Harrison, Yvonne (2003). “The impact of daylight saving time on sleep and related behaviours”. 《Sleep Medicine Reviews》 17 (4): 285-292. doi:dx.doi.org/10.1016/j.smrv.2012.10.001 |doi= 값 확인 필요 (도움말). 2016년 1월 3일에 확인함. 
3. 이동 ↑ 서머타임…휴일 대혼란 경향신문, 1988.5.9.
4. 이동 ↑ "서머타임 철회하라" 동아일보, 1988.5.6.
5. 이동 ↑ 녹색성장위 "서머타임 도입" 경향신문, 2009.2.16.
6. 이동 ↑ '서머타임' 내년 4월 도입 검토 경향신문, 2009.7.28.
7. 이동 ↑ About-australia our-country time
8. 이동 ↑ Daylight Saving Time - When do we change our clocks?
9. 이동 ↑ “Egypt to cancel daylight saving time”. Egypt Independent. 2011년 4월 20일. 2013년 12월 8일에 확인함. 
10. 이동 ↑ “러시아, '서머타임제' 논쟁에 종지부”. 연합뉴스. 2011년 3월 22일. 2013년 12월 8일에 확인함. 
11. 이동 ↑ Kotchen, Matthew; Grant, Laura (2011). “Does Daylight Saving Time Save Energy? Evidence from a Natural Experiment in Indiana”. 《The Review of Economics and Statistics》 93 (4): 1172-1185. 2015년 12월 13일에 확인함. 
12. 이동 ↑ 도현, 안. “과학으로 본 일광절약제: 과연 전기 절약할까?”. 2015년 12월 13일에 확인함. 
13. 이동 ↑ Harrison, Yvonne (2003). “The impact of daylight saving time on sleep and related behaviours”. 《Sleep Medicine Reviews》 17 (4): 285-292. doi:dx.doi.org/10.1016/j.smrv.2012.10.001 |doi= 값 확인 필요 (도움말). 2016년 1월 3일에 확인함. 
14. 이동 ↑ John, Gaski; Jeff, Sagarin (2011). “Detrimental effects of daylight-saving time on SAT scores.” (PDF). 《Journal of Neuroscience, Psychology, and Economics》 4 (1): 44-53. doi:http://dx.doi.org/10.1037/a0020118 |doi= 값 확인 필요 (도움말). 
15. 이동 ↑ Wagner, Davis; Barnes, Christopher; Lim, Vivien; Lance, Fferr (2012). “Lost sleep and cyberloafing: evidence from the laboratory and a daylight saving time quasi-experiment.” (PDF). 《Journal of Applied Psychology》 97 (5): 1068-1076. doi:http://dx.doi.org/10.1037/a0027557 |doi= 값 확인 필요 (도움말). 2016년 1월 3일에 확인함. 

바깥 고리[편집]

위키미디어 공용에 관련 미디어 분류가 있습니다. 일광 절약 시간제

• (영어) "Legal Time 2014" - ITU-T

전거 통제	NDL: 00570171

원본 주소 "https://ko.wikipedia.org/w/index.php?title=일광_절약_시간제&oldid=17264135"

분류:

• 시간대
• 일광 절약 시간제
  

From Wikipedia, the free encyclopedia

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This article is about the concept of daylight saving time. For local implementations, see Daylight saving time by country.

"Daylight Saving" redirects here. For the play by Nick Enright, see Daylight Saving (play).

"Summer time" and "DST" redirect here. For other uses, see Summer time (disambiguation) and DST (disambiguation).

Daylight saving time regions as of December 2016^[update]:

  Northern hemisphere summer

  Southern hemisphere summer

  Formerly used daylight savings or permanent daylight savings

  Never used daylight savings

Daylight saving time (DST) or summer time is the practice of advancing clocks during summer months by one hour so that evening daylight lasts an hour longer, while sacrificing normal sunrise times. Typically, regions with summer time adjust clocks forward one hour close to the start of spring and adjust them backward in the autumn to standard time.^[1]

New Zealander George Hudson proposed the idea of daylight saving in 1895.^[2] The German Empire and Austria-Hungary organized the first nationwide implementation, starting on April 30, 1916. Many countries have used it at various times since then, particularly since the energy crisis of the 1970s.

The practice has both advocates and critics.^[1] Putting clocks forward benefits retailing, sports, and other activities that exploit sunlight after working hours,^[3] but can cause problems for outdoor entertainment and other activities tied to sunlight, such as farming.^[4][5] Though some early proponents of DST aimed to reduce evening use of incandescent lighting—once a primary use of electricity^[6]—today's heating and cooling usage patterns differ greatly, and research about how DST affects energy use is limited and contradictory.^[7]

DST clock shifts sometimes complicate timekeeping, and can disrupt travel, billing, record keeping, medical devices, heavy equipment,^[8] and sleep patterns.^[9] Computer software often adjusts clocks automatically, but policy changes by various jurisdictions of DST dates and timings may be confusing.^[10]

Contents

 [hide] 

• 1 Rationale
• 2 History
• 3 Procedure
• 4 Politics
• 5 Dispute over benefits and drawbacks
  • 5.1 Energy use
  • 5.2 Economic effects
  • 5.3 Public safety
  • 5.4 Health
  • 5.5 Complexity
• 6 Terminology
• 7 Computing
  • 7.1 IANA time zone database
  • 7.2 Microsoft Windows
• 8 Permanent daylight saving time
• 9 By country and region
• 10 References
• 11 Further reading
• 12 External links

Rationale[edit]

Industrialized societies generally follow a clock-based schedule for daily activities that do not change throughout the course of the year. The time of day that individuals begin and end work or school, and the coordination of mass transit, for example, usually remain constant year-round. In contrast, an agrarian society's daily routines for work and personal conduct are more likely governed by the length of daylight hours^[11][12] and by solar time, which change seasonally because of the Earth's axial tilt. North and south of the tropics daylight lasts longer in summer and shorter in winter, with the effect becoming greater as one moves away from the tropics.

By synchronously resetting all clocks in a region to one hour ahead of standard time (one hour "fast"), individuals who follow such a year-round schedule will wake an hour earlier than they would have otherwise; they will begin and complete daily work routines an hour earlier, and they will have available to them an extra hour of daylight after their workday activities.^[13][14] However, they will have one less hour of daylight at the start of each day, making the policy less practical during winter.^[15][16]

While the times of sunrise and sunset change at roughly equal rates as the seasons change, proponents of Daylight Saving Time argue that most people prefer a greater increase in daylight hours after the typical "nine to five" workday.^[17][18] Supporters have also argued that DST decreases energy consumption by reducing the need for lighting and heating, but the actual effect on overall energy use is heavily disputed.

The manipulation of time at higher latitudes (for example Iceland, Nunavut or Alaska) has little impact on daily life, because the length of day and night changes more extremely throughout the seasons (in comparison to other latitudes), and thus sunrise and sunset times are significantly out of phase with standard working hours regardless of manipulations of the clock.^[19] DST is also of little use for locations near the equator, because these regions see only a small variation in daylight in the course of the year.^[20] The effect also varies according to how far east or west the location is within its time zone, with locations farther east inside the time zone benefiting more from DST than locations farther west in the same time zone.^[21]

History[edit]

Ancient water clock that lets hour lengths vary with season.

Although they did not fix their schedules to the clock in the modern sense, ancient civilizations adjusted daily schedules to the sun more flexibly than DST does, often dividing daylight into twelve hours regardless of daytime, so that each daylight hour was longer during summer.^[22] For example, Roman water clocks had different scales for different months of the year: at Rome's latitude the third hour from sunrise, hora tertia, started by modern standards at 09:02 solar time and lasted 44 minutes at the winter solstice, but at the summer solstice it started at 06:58 and lasted 75 minutes (see also: Roman timekeeping).^[23] After ancient times, equal-length civil hours eventually supplanted unequal, so civil time no longer varies by season. Unequal hours are still used in a few traditional settings, such as some monasteries of Mount Athos^[24] and all Jewish ceremonies.^[25]

During his time as an American envoy to France, Benjamin Franklin, publisher of the old English proverb, "Early to bed, and early to rise, makes a man healthy, wealthy and wise",^[26][27] anonymously published a letter suggesting that Parisians economize on candles by rising earlier to use morning sunlight.^[28] This 1784 satire proposed taxing window shutters, rationing candles, and waking the public by ringing church bells and firing cannons at sunrise.^[29] Despite common misconception, Franklin did not actually propose DST; 18th-century Europe did not even keep precise schedules. However, this soon changed as rail transport and communication networks came to require a standardization of time unknown in Franklin's day.^[30]

George Hudson invented modern DST, proposing it first in 1895.

Modern DST was first proposed by the New Zealand entomologist George Hudson, whose shift work job gave him leisure time to collect insects, and led him to value after-hours daylight.^[2] In 1895 he presented a paper to the Wellington Philosophical Society proposing a two-hour daylight-saving shift,^[13] and after considerable interest was expressed in Christchurch, he followed up in an 1898 paper.^[31] Many publications credit DST's proposal to the prominent English builder and outdoorsman William Willett,^[32] who independently conceived DST in 1905 during a pre-breakfast ride, when he observed with dismay how many Londoners slept through a large part of a summer's day.^[18] An avid golfer, he also disliked cutting short his round at dusk.^[33] His solution was to advance the clock during the summer months, a proposal he published two years later.^[34] The proposal was taken up by the Liberal Member of Parliament (MP) Robert Pearce, who introduced the first Daylight Saving Bill to the House of Commons on February 12, 1908.^[35] A select committee was set up to examine the issue, but Pearce's bill did not become law, and several other bills failed in the following years. Willett lobbied for the proposal in the UK until his death in 1915.

William Sword Frost, mayor of Orillia, Ontario, introduced daylight saving time in the municipality during his tenure from 1911 to 1912.^[36]

Starting on April 30, 1916, the German Empire and its World War I ally Austria-Hungary were the first to use DST (German: Sommerzeit) as a way to conserve coal during wartime. Britain, most of its allies, and many European neutrals soon followed suit. Russia and a few other countries waited until the next year and the United States adopted it in 1918.

Broadly speaking, Daylight Saving Time was abandoned in the years after the war (with some notable exceptions including Canada, the UK, France, and Ireland). However, it was brought back for periods of time in many different places during the following decades, and commonly during World War II. It became widely adopted, particularly in North America and Europe, starting in the 1970s as a result of the 1970s energy crisis.

Since then, the world has seen many enactments, adjustments, and repeals.^[37] For specific details, an overview is available at daylight saving time by country.

Procedure[edit]

See also: Daylight saving time by country

Clocks are advanced by one hour during the very early morning at the beginning of DST.

When DST ends, clocks are set back (as if to repeat one hour) during the very early morning. Specific times vary by jurisdiction.

In the case of the United States, where a one-hour shift occurs at 02:00 local time, in spring the clock jumps forward from the last instant of 01:59 standard time to 03:00 DST and that day has 23 hours, whereas in autumn the clock jumps backward from the last instant of 01:59 DST to 01:00 standard time, repeating that hour, and that day has 25 hours.^[38] A digital display of local time does not read 02:00 exactly at the shift to summer time, but instead jumps from 01:59:59.9 forward to 03:00:00.0.

Clock shifts are usually scheduled near a weekend midnight to lessen disruption to weekday schedules. A one-hour shift is customary.^[39] Twenty-minute and two-hour shifts have been used in the past.

Coordination strategies differ when adjacent time zones shift clocks. The European Union shifts all zones at the same instant, at 01:00 Greenwich Mean Time^[40] or 02:00 CET or 03:00 EET. The result of this procedure is that Eastern European Time is always one hour ahead of Central European Time, at the cost of the shift happening at different local times.^[41] In contrast most of North America shifts at 02:00 local time, so its zones do not shift at the same instant; for example, Mountain Time is temporarily (for one hour) zero hours ahead of Pacific Time, instead of one hour ahead, in the autumn and two hours, instead of one, ahead of Pacific Time in the spring. In the past, Australian districts went even further and did not always agree on start and end dates; for example, in 2008 most DST-observing areas shifted clocks forward on October 5 but Western Australia shifted on October 26.^[42] In some cases only part of a country shifts; for example, in the U.S., Hawaii and most of Arizona do not observe DST.^[43]

Start and end dates vary with location and year. Since 1996, European Summer Time has been observed from the last Sunday in March to the last Sunday in October; previously the rules were not uniform across the European Union.^[41] Starting in 2007, most of the United States and Canada observe DST from the second Sunday in March to the first Sunday in November, almost two-thirds of the year.^[44] The 2007 U.S. change was part of the Energy Policy Act of 2005; previously, from 1987 through 2006, the start and end dates were the first Sunday in April and the last Sunday in October, and Congress retains the right to go back to the previous dates now that an energy-consumption study has been done.^[45] Proponents for permanently retaining November as the month for ending DST point to Halloween as a reason to delay the change—to provide extra daylight on October 31.

In early 2008 central Brazil was one, two, or three hours ahead of eastern U.S., depending on the date.

Beginning and ending dates are roughly the reverse in the southern hemisphere. For example, mainland Chile observed DST from the second Saturday in October to the second Saturday in March, with transitions at 24:00 local time.^[46] The time difference between the United Kingdom and mainland Chile could therefore be five hours during the northern summer, three hours during the southern summer and four hours a few weeks per year because of mismatch of changing dates.

DST is generally not observed near the equator, where sunrise times do not vary enough to justify it. Some countries observe it only in some regions; for example, southern Brazil observes it while equatorial Brazil does not.^[47] Only a minority of the world's population uses DST because Asia and Africa generally do not observe it.

Politics[edit]

Daylight saving has caused controversy since it began.^[1] Winston Churchill argued that it enlarges "the opportunities for the pursuit of health and happiness among the millions of people who live in this country"^[48] and pundits have dubbed it "Daylight Slaving Time".^[49] Historically, retailing, sports, and tourism interests have favored daylight saving, while agricultural and evening entertainment interests have opposed it, and its initial adoption had been prompted by energy crises and war.^[50]

The fate of Willett's 1907 proposal illustrates several political issues involved. The proposal attracted many supporters, including Arthur Balfour, Churchill, David Lloyd George, Ramsay MacDonald, Edward VII (who used half-hour DST at Sandringham or "Sandringham time"), the managing director of Harrods, and the manager of the National Bank. However, the opposition was stronger: it included Prime Minister H. H. Asquith, Christie (the Astronomer Royal), George Darwin, Napier Shaw (director of the Meteorological Office), many agricultural organizations, and theatre owners. After many hearings the proposal was narrowly defeated in a parliamentary committee vote in 1909. Willett's allies introduced similar bills every year from 1911 through 1914, to no avail.^[51] The U.S. was even more skeptical: Andrew Peters introduced a DST bill to the United States House of Representatives in May 1909, but it soon died in committee.^[52]

Retailers generally favor DST. United Cigar Stores hailed a 1918 DST bill.

After Germany led the way with starting DST (German: Sommerzeit) during World War I on April 30, 1916 together with its allies to alleviate hardships from wartime coal shortages and air raid blackouts, the political equation changed in other countries; the United Kingdom used DST first on May 21, 1916.^[53] U.S. retailing and manufacturing interests led by Pittsburgh industrialist Robert Garland soon began lobbying for DST, but were opposed by railroads. The U.S.'s 1917 entry to the war overcame objections, and DST was established in 1918.^[54]

The war's end swung the pendulum back. Farmers continued to dislike DST, and many countries repealed it after the war. Britain was an exception: it retained DST nationwide but over the years adjusted transition dates for several reasons, including special rules during the 1920s and 1930s to avoid clock shifts on Easter mornings. Now under a European Community directive summer time begins annually on the last Sunday in March, which may be Easter Sunday (as in 2016).^[41] The U.S. was more typical: Congress repealed DST after 1919. President Woodrow Wilson, like Willett an avid golfer, vetoed the repeal twice but his second veto was overridden.^[55] Only a few U.S. cities retained DST locally thereafter,^[56] including New York so that its financial exchanges could maintain an hour of arbitrage trading with London, and Chicago and Cleveland to keep pace with New York.^[57] Wilson's successor Warren G. Harding opposed DST as a "deception". Reasoning that people should instead get up and go to work earlier in the summer, he ordered District of Columbia federal employees to start work at 08:00 rather than 09:00 during summer 1922. Some businesses followed suit though many others did not; the experiment was not repeated.^[14]

Since Germany's adoption in 1916, the world has seen many enactments, adjustments, and repeals of DST, with similar politics involved.^[58]

The history of time in the United States includes DST during both world wars, but no standardization of peacetime DST until 1966.^[59][60] In May 1965, for two weeks, St. Paul, Minnesota and Minneapolis, Minnesota were on different times, when the capital city decided to join most of the nation by starting Daylight Saving Time while Minneapolis opted to follow the later date set by state law.^[61] In the mid-1980s, Clorox (parent of Kingsford Charcoal) and 7-Eleven provided the primary funding for the Daylight Saving Time Coalition behind the 1987 extension to U.S. DST, and both Idaho senators voted for it based on the premise that during DST fast-food restaurants sell more French fries, which are made from Idaho potatoes.^[3]

In 1992, after a three-year trial of daylight saving in Queensland, Australia, a referendum on daylight saving was held and defeated with a 54.5% 'no' vote – with regional and rural areas strongly opposed, while those in the metropolitan south-east were in favor.^[62] In 2005, the Sporting Goods Manufacturers Association and the National Association of Convenience Stores successfully lobbied for the 2007 extension to U.S. DST.^[63] In December 2008, the Daylight Saving for South East Queensland (DS4SEQ) political party was officially registered in Queensland, advocating the implementation of a dual-time zone arrangement for daylight saving in South East Queensland while the rest of the state maintains standard time.^[64] DS4SEQ contested the March 2009 Queensland state election with 32 candidates and received one percent of the statewide primary vote, equating to around 2.5% across the 32 electorates contested.^[65] After a three-year trial, more than 55% of Western Australians voted against DST in 2009, with rural areas strongly opposed.^[66] On April 14, 2010, after being approached by the DS4SEQ political party, Queensland Independent member Peter Wellington, introduced the Daylight Saving for South East Queensland Referendum Bill 2010 into the Queensland parliament, calling for a referendum at the next state election on the introduction of daylight saving into South East Queensland under a dual-time zone arrangement.^[67] The Bill was defeated in the Queensland parliament on June 15, 2011.^[68]

In the UK the Royal Society for the Prevention of Accidents supports a proposal to observe SDST's additional hour year-round, but is opposed in some industries, such as postal workers and farmers, and particularly by those living in the northern regions of the UK.^[12]

In some Muslim countries, DST is temporarily abandoned during Ramadan (the month when no food should be eaten between sunrise and sunset), since the DST would delay the evening dinner. Ramadan took place in July and August in 2012. This concerns at least Morocco^[69][70] and Palestine, although Iran keeps DST during Ramadan.^[71] Most Muslim countries do not use DST, partially for this reason.

The 2011 declaration by Russia that it would stay in DST all year long was subsequently followed by a similar declaration from Belarus.^[72] Russia's plan generated widespread complaints due to the dark of wintertime morning, and thus was abandoned in 2014.^[73] The country changed its clocks to Standard Time on October 26, 2014 and intends to stay there permanently.^[74]

Dispute over benefits and drawbacks[edit]

William Willett independently proposed DST in 1907 and advocated it tirelessly.^[75]

Proponents of DST generally argue that it saves energy, promotes outdoor leisure activity in the evening (in summer), and is therefore good for physical and psychological health, reduces traffic accidents, reduces crime, or is good for business. Groups that tend to support DST are urban workers, retail businesses, outdoor sports enthusiasts and businesses, tourism operators, and others who benefit from increased light during the evening in summer.

Opponents argue that actual energy savings are inconclusive,^[76] that DST increases health risks such as heart attack,^[76] that DST can disrupt morning activities, and that the act of changing clocks twice a year is economically and socially disruptive and cancels out any benefit. Farmers have tended to oppose DST.^[77][78]

Common agreement about the day's layout or schedule confers so many advantages that a standard DST schedule has generally been chosen over ad hoc efforts to get up earlier.^[79] The advantages of coordination are so great that many people ignore whether DST is in effect by altering their nominal work schedules to coordinate with television broadcasts or daylight.^[80] DST is commonly not observed during most of winter, because its mornings are darker; workers may have no sunlit leisure time, and children may need to leave for school in the dark.^[15] Since DST is applied to many varying communities, its effects may be very different depending on their culture, light levels, geography, and climate; that is why it is hard to make generalized conclusions about the absolute effects of the practice. Some areas may adopt DST simply as a matter of coordination with others rather than for any direct benefits.

Energy use[edit]

DST's potential to save energy comes primarily from its effects on residential lighting, which consumes about 3.5% of electricity in the United States and Canada.^[7] Delaying the nominal time of sunset and sunrise reduces the use of artificial light in the evening and increases it in the morning. As Franklin's 1784 satire pointed out, lighting costs are reduced if the evening reduction outweighs the morning increase, as in high-latitude summer when most people wake up well after sunrise. An early goal of DST was to reduce evening usage of incandescent lighting, once a primary use of electricity.^[6] Although energy conservation remains an important goal,^[81] energy usage patterns have greatly changed since then, and recent research is limited and reports contradictory results. Electricity use is greatly affected by geography, climate, and economics, making it hard to generalize from single studies.^[7]

• The United States Department of Transportation (DOT) concluded in 1975 that DST might reduce the country's electricity usage by 1% during March and April,^[7] but the National Bureau of Standards (NBS) reviewed the DOT study in 1976 and found no significant savings.^[15]
• In 2000, when parts of Australia began DST in late winter, overall electricity consumption did not decrease, but the morning peak load and prices increased.^[82]
• In Western Australia during summer 2006–2007, DST increased electricity consumption during hotter days and decreased it during cooler days, with consumption rising 0.6% overall.^[83]
• Although a 2007 study estimated that introducing DST to Japan would reduce household lighting energy consumption,^[84] a 2007 simulation estimated that DST would increase overall energy use in Osaka residences by 0.13%, with a 0.02% decrease due to less lighting more than outweighed by a 0.15% increase due to extra cooling; neither study examined non-residential energy use.^[85] This is probably because DST's effect on lighting energy use is mainly noticeable in residences.^[7]
• A 2007 study found that the earlier start to DST that year had little or no effect on electricity consumption in California.^[86]
• A 2007 study estimated that winter daylight saving would prevent a 2% increase in average daily electricity consumption in Great Britain.^[87] This paper was revised in October 2009.^[88]
• A 2008 study examined billing data in Indiana before and after it adopted DST in 2006, and concluded that DST increased overall residential electricity consumption by 1% to 4%, due mostly to extra afternoon cooling and extra morning heating; the main increases came in the fall. A study estimated the overall annual cost of DST to Indiana households $9 million, with an additional $1.7–5.5 million for social costs due to increased pollution.^[89]
• The United States Department of Energy (DOE) concluded in a 2008 report that the 2007 United States extension of DST saved 0.5% of electricity usage during the extended period.^[90] This report analyzed only the extension, not the full eight months of DST, and did not examine the use of heating fuels.^[91]

Several studies have suggested that DST increases motor fuel consumption.^[7] The 2008 DOE report found no significant increase in motor gasoline consumption due to the 2007 United States extension of DST.^[90]

Economic effects[edit]

Retailers, sporting goods makers, and other businesses benefit from extra afternoon sunlight, as it induces customers to shop and to participate in outdoor afternoon sports.^[92] In 1984, Fortune magazine estimated that a seven-week extension of DST would yield an additional $30 million for 7-Eleven stores, and the National Golf Foundation estimated the extension would increase golf industry revenues $200 million to $300 million.^[93] A 1999 study estimated that DST increases the revenue of the European Union's leisure sector by about 3%.^[7]

Conversely, DST can adversely affect farmers,^[76] parents of young children,^[76] and others whose hours are set by the sun and they have traditionally opposed the practice,^[4] although some farmers are neutral.^[94] One reason why farmers oppose DST is that grain is best harvested after dew evaporates, so when field hands arrive and leave earlier in summer their labor is less valuable.^[11] Dairy farmers are another group who complain of the change. Their cows are sensitive to the timing of milking, so delivering milk earlier disrupts their systems.^[78][95] Today some farmers' groups are in favor of DST.^[96]

DST also hurts prime-time television broadcast ratings,^[5][76] drive-ins and other theaters.^[97]

Changing clocks and DST rules has a direct economic cost, entailing extra work to support remote meetings, computer applications and the like. For example, a 2007 North American rule change cost an estimated $500 million to $1 billion,^[98] and Utah State University economist William F. Shughart II has estimated the lost opportunity cost at around $1.7 billion USD.^[76] Although it has been argued that clock shifts correlate with decreased economic efficiency, and that in 2000 the daylight-saving effect implied an estimated one-day loss of $31 billion on U.S. stock exchanges,^[99] the estimated numbers depend on the methodology.^[100] The results have been disputed,^[101] and the original authors have refuted the points raised by disputers.^[102]

Public safety[edit]

In 1975 the U.S. DOT conservatively identified a 0.7% reduction in traffic fatalities during DST, and estimated the real reduction at 1.5% to 2%,^[103] but the 1976 NBS review of the DOT study found no differences in traffic fatalities.^[15] In 1995 the Insurance Institute for Highway Safety estimated a reduction of 1.2%, including a 5% reduction in crashes fatal to pedestrians.^[104] Others have found similar reductions.^[105] Single/Double Summer Time (SDST), a variant where clocks are one hour ahead of the sun in winter and two in summer, has been projected to reduce traffic fatalities by 3% to 4% in the UK, compared to ordinary DST.^[106] However, accidents do increase by as much as 11% during the two weeks that follow the end of British Summer Time.^[107] It is not clear whether sleep disruption contributes to fatal accidents immediately after the spring clock shifts.^[108] A correlation between clock shifts and traffic accidents has been observed in North America and the UK but not in Finland or Sweden. If this effect exists, it is far smaller than the overall reduction in traffic fatalities.^[109] A 2009 U.S. study found that on Mondays after the switch to DST, workers sleep an average of 40 minutes less, and are injured at work more often and more severely.^[110]

In the 1970s the U.S. Law Enforcement Assistance Administration (LEAA) found a reduction of 10% to 13% in Washington, D.C.'s violent crime rate during DST. However, the LEAA did not filter out other factors, and it examined only two cities and found crime reductions only in one and only in some crime categories; the DOT decided it was "impossible to conclude with any confidence that comparable benefits would be found nationwide".^[111] Outdoor lighting has a marginal and sometimes even contradictory influence on crime and fear of crime.^[112]

In several countries, fire safety officials encourage citizens to use the two annual clock shifts as reminders to replace batteries in smoke and carbon monoxide detectors, particularly in autumn, just before the heating and candle season causes an increase in home fires. Similar twice-yearly tasks include reviewing and practicing fire escape and family disaster plans, inspecting vehicle lights, checking storage areas for hazardous materials, reprogramming thermostats, and seasonal vaccinations.^[113] Locations without DST can instead use the first days of spring and autumn as reminders.^[114]

Health[edit]

Clock shifts affecting apparent sunrise and sunset times at Greenwich in 2007.^[115]

Justification for Daylight Saving Time to the effect that it is a more natural adjustment for people rising with the sun.

DST has mixed effects on health. In societies with fixed work schedules it provides more afternoon sunlight for outdoor exercise.^[116] It alters sunlight exposure; whether this is beneficial depends on one's location and daily schedule, as sunlight triggers vitamin D synthesis in the skin, but overexposure can lead to skin cancer.^[117] DST may help in depression by causing individuals to rise earlier,^[118] but some argue the reverse.^[119] The Retinitis Pigmentosa Foundation Fighting Blindness, chaired by blind sports magnate Gordon Gund, successfully lobbied in 1985 and 2005 for U.S. DST extensions.^[3][63] DST shifts are associated with higher rates of ischemic stroke in the first two days after the shift, though not in the week thereafter.f^[120]

Clock shifts were found to increase the risk of heart attack by 10 percent,^[76] and to disrupt sleep and reduce its efficiency.^[9] Effects on seasonal adaptation of the circadian rhythm can be severe and last for weeks.^[121] A 2008 study found that although male suicide rates rise in the weeks after the spring transition, the relationship weakened greatly after adjusting for season.^[122] A 2008 Swedish study found that heart attacks were significantly more common the first three weekdays after the spring transition, and significantly less common the first weekday after the autumn transition.^[123] The government of Kazakhstan cited health complications due to clock shifts as a reason for abolishing DST in 2005.^[124] In March 2011, Dmitri Medvedev, president of Russia, claimed that "stress of changing clocks" was the motivation for Russia to stay in DST all year long. Officials at the time talked about an annual increase in suicides.^[125]

An unexpected adverse effect of daylight saving time may lie in the fact that an extra part of morning rush hour traffic occurs before dawn and traffic emissions then cause higher air pollution than during daylight hours.^[126]

Complexity[edit]

DST's clock shifts have the obvious disadvantage of complexity. People must remember to change their clocks; this can be time-consuming, particularly for mechanical clocks that cannot be moved backward safely.^[127] People who work across time zone boundaries need to keep track of multiple DST rules, as not all locations observe DST or observe it the same way. The length of the calendar day becomes variable; it is no longer always 24 hours. Disruption to meetings, travel, broadcasts, billing systems, and records management is common, and can be expensive.^[128] During an autumn transition from 02:00 to 01:00, a clock reads times from 01:00:00 through 01:59:59 twice, possibly leading to confusion.^[129]

The William Willett Memorial Sundial is always on DST.

Damage to a German steel facility occurred during a DST transition in 1993, when a computer timing system linked to a radio time synchronization signal allowed molten steel to cool for one hour less than the required duration, resulting in spattering of molten steel when it was poured.^[8] Medical devices may generate adverse events that could harm patients, without being obvious to clinicians responsible for care.^[130] These problems are compounded when the DST rules themselves change; software developers must test and perhaps modify many programs, and users must install updates and restart applications. Consumers must update devices such as programmable thermostats with the correct DST rules, or manually adjust the devices' clocks.^[10] A common strategy to resolve these problems in computer systems is to express time using the Coordinated Universal Time (UTC) rather than the local time zone. For example, Unix-based computer systems use the UTC-based Unix time internally.

Some clock-shift problems could be avoided by adjusting clocks continuously^[131] or at least more gradually^[132]—for example, Willett at first suggested weekly 20-minute transitions—but this would add complexity and has never been implemented.

DST inherits and can magnify the disadvantages of standard time. For example, when reading a sundial, one must compensate for it along with time zone and natural discrepancies.^[133] Also, sun-exposure guidelines such as avoiding the sun within two hours of noon become less accurate when DST is in effect.^[134]

Terminology[edit]

As explained by Richard Meade in the English Journal of the (American) National Council of Teachers of English, the form daylight savings time (with an "s") was already in 1978 much more common than the older form daylight saving time in American English ("the change has been virtually accomplished"). Nevertheless, even dictionaries such as Merriam-Webster's, American Heritage, and Oxford, which describe actual usage instead of prescribing outdated usage (and therefore also list the newer form), still list the older form first. This is because the older form is still very common in print and preferred by many editors. ("Although daylight saving time is considered correct, daylight savings time (with an "s") is commonly used.")^[135] The first two words are sometimes hyphenated (daylight-saving[s] time). Merriam-Webster's also lists the forms daylight saving (without "time"), daylight savings (without "time"), and daylight time.^[136]

In Britain, Willett's 1907 proposal^[34] used the term daylight saving, but by 1911 the term summer time replaced daylight saving time in draft legislation.^[75] Continental Europe uses similar phrases, the following examples could all be translated to "summer time": Sommerzeit in Germany, zomertijd in Dutch-speaking regions, kesäaika in Finland, horario de verano or hora de verano in Spain and heure d'été in France,^[53] hora de verão in Portugal. In Italy the term is ora legale, that is, legal time (legally enforced time) as opposed to "ora solare", solar time, in winter.^{[clarification needed]}

The name of local time typically changes when DST is observed. American English replaces standard with daylight: for example, Pacific Standard Time (PST) becomes Pacific Daylight Time (PDT). In the United Kingdom, the standard term for UK time when advanced by one hour is British Summer Time (BST), and British English typically inserts summer into other time zone names, e.g. Central European Time (CET) becomes Central European Summer Time (CEST).

The North American English mnemonic "spring forward, fall back" (also "spring ahead ...", "spring up ...", and "... fall behind") helps people remember which direction to shift clocks.^[1]

Computing[edit]

A 2001 US public service advertisement reminded people to adjust clocks.

Changes to DST rules cause problems in existing computer installations. For example, the 2007 change to DST rules in North America required that many computer systems be upgraded, with the greatest impact on e-mail and calendar programs. The upgrades required a significant effort by corporate information technologists.^[137]

Some applications standardize on UTC to avoid problems with clock shifts and time zone differences.^[138] Likewise, most modern operating systems internally handle and store all times as UTC and only convert to local time for display.^[139][140]

However, even if UTC is used internally, the systems still require information on time zones to correctly calculate local time where it is needed. Many systems in use today base their date/time calculations from data derived from the IANA time zone database also known as zoneinfo.

IANA time zone database[edit]

The IANA time zone database maps a name to the named location's historical and predicted clock shifts. This database is used by many computer software systems, including most Unix-like operating systems, Java, and the Oracle RDBMS;^[141] HP's "tztab" database is similar but incompatible.^[142] When temporal authorities change DST rules, zoneinfo updates are installed as part of ordinary system maintenance. In Unix-like systems the TZ environment variable specifies the location name, as in TZ=':America/New_York'. In many of those systems there is also a system-wide setting that is applied if the TZ environment variable is not set: this setting is controlled by the contents of the /etc/localtime file, which is usually a symbolic link or hard link to one of the zoneinfo files. Internal time is stored in timezone-independent epoch time; the TZ is used by each of potentially many simultaneous users and processes to independently localize time display.

Older or stripped-down systems may support only the TZ values required by POSIX, which specify at most one start and end rule explicitly in the value. For example, TZ='EST5EDT,M3.2.0/02:00,M11.1.0/02:00' specifies time for the eastern United States starting in 2007. Such a TZ value must be changed whenever DST rules change, and the new value applies to all years, mishandling some older timestamps.^[143]

Microsoft Windows[edit]

As with zoneinfo, a user of Microsoft Windows configures DST by specifying the name of a location, and the operating system then consults a table of rule sets that must be updated when DST rules change. Procedures for specifying the name and updating the table vary with release. Updates are not issued for older versions of Microsoft Windows.^[144] Windows Vista supports at most two start and end rules per time zone setting. In a Canadian location observing DST, a single Vista setting supports both 1987–2006 and post-2006 time stamps, but mishandles some older time stamps. Older Microsoft Windows systems usually store only a single start and end rule for each zone, so that the same Canadian setting reliably supports only post-2006 time stamps.^[145]

These limitations have caused problems. For example, before 2005, DST in Israel varied each year and was skipped some years. Windows 95 used rules correct for 1995 only, causing problems in later years. In Windows 98, Microsoft marked Israel as not having DST, forcing Israeli users to shift their computer clocks manually twice a year. The 2005 Israeli Daylight Saving Law established predictable rules using the Jewish calendar but Windows zone files could not represent the rules' dates in a year-independent way. Partial workarounds, which mishandled older time stamps, included manually switching zone files every year^[146] and a Microsoft tool that switches zones automatically.^[147] In 2013, Israel standardized its daylight saving time according to the Gregorian calendar.^[148]

Microsoft Windows keeps the system real-time clock in local time. This causes several problems, including compatibility when multi booting with operating systems that set the clock to UTC, and double-adjusting the clock when multi booting different Windows versions, such as with a rescue boot disk. This approach is a problem even in Windows-only systems: there is no support for per-user timezone settings, only a single system-wide setting. In 2008 Microsoft hinted that future versions of Windows will partially support a Windows registry entry RealTimeIsUniversal that had been introduced many years earlier, when Windows NT supported RISC machines with UTC clocks, but had not been maintained.^[149] Since then at least two fixes related to this feature have been published by Microsoft.^[150][151]

The NTFS file system used by recent versions of Windows stores the file with a UTC time stamp, but displays it corrected to local—or seasonal—time. However, the FAT filesystem commonly used on removable devices stores only the local time. Consequently, when a file is copied from the hard disk onto separate media, its time will be set to the current local time. If the time adjustment is changed, the timestamps of the original file and the copy will be different. The same effect can be observed when compressing and uncompressing files with some file archivers. It is the NTFS file that changes seen time. This effect should be kept in mind when trying to determine if a file is a duplicate of another, although there are other methods of comparing files for equality (such as using a checksum algorithm).

Permanent daylight saving time[edit]

A move to "permanent daylight saving time" (staying on summer hours all year with no time shifts) is sometimes advocated, and has in fact been implemented in some jurisdictions such as Argentina, Chile,^[152] Iceland, Singapore, Uzbekistan, Belarus^[78] and Turkey. Advocates cite the same advantages as normal DST without the problems associated with the twice yearly time shifts. However, many remain unconvinced of the benefits, citing the same problems and the relatively late sunrises, particularly in winter, that year-round DST entails.^[16] Russia switched to permanent DST from 2011 to 2014, but the move proved unpopular because of the late sunrises in winter, so the country switched permanently back to "standard" or "winter" time in 2014.^[153] Many European countries have also implemented permanent summer time during World War II.^{[citation needed]}

By country and region[edit]

• Time portal

• Daylight saving time by country
• Africa
• Asia
• Brazil
• Europe
• North and South America
• Oceania
• United States

References[edit]

1. ^ Jump up to: ^{a b c d} DST practices and controversies:
   • Michael Downing (2005). Spring Forward: The Annual Madness of Daylight Saving Time. Shoemaker & Hoard. ISBN 1-59376-053-1. 
   • David Prerau (2005). Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time. Thunder's Mouth Press. ISBN 1-56025-655-9.  The British version, focusing on the UK, is Saving the Daylight: Why We Put the Clocks Forward. Granta Books. ISBN 1-86207-796-7. 
2. ^ Jump up to: ^{a b} Gibbs, George. "Hudson, George Vernon". Dictionary of New Zealand Biography. Ministry for Culture and Heritage. Retrieved March 22, 2015. 
3. ^ Jump up to: ^{a b c} James C. Benfield (May 24, 2001). "Statement to the U.S. House, Committee on Science, Subcommittee on Energy". Energy Conservation Potential of Extended and Double Daylight Saving Time. Serial 107-30. 
4. ^ Jump up to: ^{a b} Effect on those whose hours are set by the sun:
   • Spring Forward. pp. 19–33. 
   • Seize the Daylight. pp. 103–110, 149–151, 198. 
5. ^ Jump up to: ^{a b} Rick Kissell (March 20, 2007). "Daylight-saving dock ratings". Variety. 
6. ^ Jump up to: ^{a b} Roscoe G. Bartlett (May 24, 2001). "Statement to the US House, Committee on Science, Subcommittee on Energy". Energy Conservation Potential of Extended and Double Daylight Saving Time. Serial 107-30. 
7. ^ Jump up to: ^{a b c d e f g} Myriam B.C. Aries; Guy R. Newsham (2008). "Effect of daylight saving time on lighting energy use: a literature review". Energy Policy. 36 (6): 1858–1866. doi:10.1016/j.enpol.2007.05.021. 
8. ^ Jump up to: ^{a b} Peter G. Neumann (1994). "Computer date and time problems". Computer-Related Risks. Addison–Wesley. ISBN 0-201-55805-X. 
9. ^ Jump up to: ^{a b} Tuuli A. Lahti; Sami Leppämäki; Jouko Lönnqvist; Timo Partonen (2008). "Transitions into and out of daylight saving time compromise sleep and the rest–activity cycles". BMC Physiology. 8: 3. doi:10.1186/1472-6793-8-3. PMC 2259373. PMID 18269740. 
10. ^ Jump up to: ^{a b} Stephen Tong; Joseph Williams (2007). "Are you prepared for daylight saving time in 2007?". IT Professional. 9 (1): 36–41. doi:10.1109/MITP.2007.2. 
11. ^ Jump up to: ^{a b} "Daylight savings time". Session Weekly. Minnesota House Public Information Office. 1991. Retrieved August 7, 2013. 
12. ^ Jump up to: ^{a b} "Single/Double Summer Time policy paper" (PDF). Royal Society for the Prevention of Accidents. October 2006. Archived from the original (PDF) on September 13, 2012. 
13. ^ Jump up to: ^{a b} G. V. Hudson (1895). "On seasonal time-adjustment in countries south of lat. 30°". Transactions and Proceedings of the New Zealand Institute. 28: 734. 
14. ^ Jump up to: ^{a b} Seize the Daylight. pp. 115–118. 
15. ^ Jump up to: ^{a b c d} Mark Gurevitz (March 7, 2007). "Daylight saving time". Order Code RS22284. Congressional Research Service. 
16. ^ Jump up to: ^{a b} Handwerk, Brian. "Permanent Daylight Saving Time? Might Boost Tourism, Efficiency". National Geographic. Retrieved January 5, 2012. 
17. Jump up ^ Mikkelson, David (March 13, 2016). "Daylight Saving Time". Snopes. Retrieved October 17, 2016. 
18. ^ Jump up to: ^{a b} "100 years of British Summer Time". National Maritime Museum. 2008. 
19. Jump up ^ "Bill would do away with daylight savings time in Alaska". Peninsula Clarion. March 17, 2002. Retrieved January 5, 2013. Because of our high latitudinal location, the extremities in times for sunrise and sunset are more exaggerated for Alaska than anywhere else in the country," Lancaster said. "This makes Alaska less affected by savings from daylight-saving time. 
20. Jump up ^ Rosenberg, Matt (2016). "Daylight Saving Time (Also Known as Daylight Savings Time)". About. Retrieved October 17, 2016. 
21. Jump up ^ Swanson, Anna (March 11, 2016). "Why daylight saving time isn't as terrible as people think". The Washington Post. 
22. Jump up ^ Berthold (1918). "Daylight saving in ancient Rome". The Classical Journal. 13 (6): 450–451. 
23. Jump up ^ Jérôme Carcopino (1968). "The days and hours of the Roman calendar". Daily Life in Ancient Rome: The People and the City at the Height of the Empire. Yale University Press. ISBN 0-300-00031-6. 
24. Jump up ^ Robert Kaplan (2003). "The holy mountain". The Atlantic. 292 (5): 138–141. 
25. Jump up ^ Hertzel Hillel Yitzhak (2006). "When to recite the blessing". Tzel HeHarim: Tzitzit. Nanuet, NY: Feldheim. pp. 53–58. ISBN 1-58330-292-1. 
26. Jump up ^ Manser, Martin H. (2007). The Facts on File dictionary of proverbs. Infobase Publishing. p. 70. Retrieved October 26, 2011. 
27. Jump up ^ Benjamin Franklin; William Temple Franklin; William Duane (1834). Memoirs of Benjamin Franklin. McCarty & Davis. p. 477. Retrieved October 20, 2016. 
28. Jump up ^ Seymour Stanton Block (2006). "Benjamin Franklin: America's inventor". American History. 
29. Jump up ^ Benjamin Franklin, writing anonymously (April 26, 1784). "Aux auteurs du Journal". Journal de Paris (in French) (117): 511–513.  Its first publication was in the journal's "Économie" section, in a French translation of the English original. The revised English version [cited February 13, 2009] is commonly called "An Economical Project", a title that is not Franklin's; see A.O. Aldridge (1956). "Franklin's essay on daylight saving". American Literature. 28 (1): 23–29. doi:10.2307/2922719. 
30. Jump up ^ Eviatar Zerubavel (1982). "The standardization of time: a sociohistorical perspective". The American Journal of Sociology. 88 (1): 1–23. doi:10.1086/227631. 
31. Jump up ^ G. V. Hudson (1898). "On seasonal time". Transactions and Proceedings of the New Zealand Institute. 31: 577–588. 
32. Jump up ^ "New Zealand time". New Zealand Geographer. 4 (1): 104. 1948. doi:10.1111/j.1745-7939.1948.tb01515.x. 
33. Jump up ^ Seize the Daylight. p. 3. 
34. ^ Jump up to: ^{a b} Willett pamphlet: William Willett (1907). The waste of daylight (1st ed.). 
35. Jump up ^ "DAYLIGHT SAVING BILL". Parliamentary Debates (Hansard). House of Commons. February 12, 1908. col. 155–156. 
36. Jump up ^ Moro, Teviah (July 16, 2009). "Faded Memories for Sale". Orillia Packet and Times. Orillia, Ontario. Retrieved October 20, 2016. 
37. Jump up ^ Seize the Daylight. pp. 51–89. 
38. Jump up ^ 15 U.S.C. § 260a.
39. Jump up ^ "Information for visitors". Lord Howe Island Tourism Association. Retrieved April 20, 2009. 
40. Jump up ^ National Physical Laboratory (March 31, 2016). "At what time should clocks go forward or back for summer time (FAQ - Time)". Retrieved October 17, 2016. The time at which summer time begins and ends is given in the relevant EU Directive and UK Statutory Instrument as 1 a.m. Greenwich Mean Time (GMT) ... All time signals are based on Coordinated Universal Time (UTC), which can be almost one second ahead of, or behind, GMT so there is a brief period in the UK when the directive is not being strictly followed. 
41. ^ Jump up to: ^{a b c} Joseph Myers (July 17, 2009). "History of legal time in Britain". 
42. Jump up ^ "Implementation dates of daylight saving time within Australia". Bureau of Meteorology. September 22, 2009. 
43. Jump up ^ Seize the Daylight. pp. 179–180. 
44. Jump up ^ Tom Baldwin (March 12, 2007). "US gets summertime blues as the clocks go forward 3 weeks early". The Times. London. 
45. Jump up ^ "Energy Policy Act of 2005, Public Law 109-58 § 110". August 8, 2005. 
46. Jump up ^ "Historia de la hora oficial de Chile" (in Spanish). Chilean Hydrographic and Oceanographic Service. October 1, 2008. 
47. Jump up ^ "Decretos sobre o Horário de Verão no Brasil" (in Portuguese). Time Service Dept., National Observatory, Brazil. September 16, 2008. 
48. Jump up ^ Winston S. Churchill (April 28, 1934). "A silent toast to William Willett". Pictorial Weekly. 
49. Jump up ^ Seize the Daylight. p. 117. 
50. Jump up ^ Seize the Daylight. p. xi. 
51. Jump up ^ Seize the Daylight. pp. 12–24. 
52. Jump up ^ Seize the Daylight. pp. 72–73. 
53. ^ Jump up to: ^{a b} Seize the Daylight. pp. 51–70. 
54. Jump up ^ Seize the Daylight. pp. 80–101. 
55. Jump up ^ Seize the Daylight. pp. 103–110. 
56. Jump up ^ Robert Garland (1927). Ten years of daylight saving from the Pittsburgh standpoint. Carnegie Library of Pittsburgh. OCLC 30022847. 
57. Jump up ^ Spring Forward. pp. 47–48. 
58. Jump up ^ David P. Baron (2005). "The politics of the extension of daylight saving time". Business and its Environment (5th ed.). Prentice Hall. ISBN 0-13-187355-5. 
59. Jump up ^ Seize the Daylight. pp. 147–155, 175–180. 
60. Jump up ^ Ian R. Bartky; Elizabeth Harrison (1979). "Standard and daylight-saving time". Scientific American. 240 (5): 46–53. doi:10.1038/scientificamerican0579-46. ISSN 0036-8733. 
61. Jump up ^ May 1965, Minnesota Mayhem.
62. Jump up ^ "1992 Queensland Daylight Saving Referendum" (PDF). Retrieved July 25, 2010. 
63. ^ Jump up to: ^{a b} Alex Beam (July 26, 2005). "Dim-witted proposal for daylight time". Boston Globe. 
64. Jump up ^ "Daylight Saving group launched as new Qld political party". ABC News. December 14, 2008. Retrieved July 25, 2010. 
65. Jump up ^ "Total Candidates Nominated for Election by Party – 2009 State Election". Electoral Commission of Queensland (ECQ). Retrieved June 19, 2010. 
66. Jump up ^ Paige Taylor (May 18, 2009). "Daylight saving at a sunset out west". The Australian. 
67. Jump up ^ "Daylight Saving for South East Queensland Referendum Bill 2010" (PDF). April 14, 2010. Retrieved July 25, 2010. 
68. Jump up ^ "Daylight saving silence 'deafening'". June 16, 2011. Retrieved June 19, 2011. 
69. Jump up ^ Time and Date (March 16, 2012). "Morocco formalizes yearly Daylight Saving Time". Retrieved October 20, 2016. 
70. Jump up ^ Time and Date (September 28, 2013). "Morocco extends DST to October 27, 2013". Retrieved October 20, 2016. 
71. Jump up ^ "Time zone in Tehran". Retrieved October 28, 2014. 
72. Jump up ^ Time and Date (September 19, 2011). "Eternal Daylight Saving Time (DST) in Belarus". Retrieved October 20, 2016. 
73. Jump up ^ "Russia abandons year-round daylight-saving time". AP. July 1, 2014. Retrieved October 21, 2014. 
74. Jump up ^ "Russian clocks go back for last time". BBC. October 25, 2014. Retrieved October 25, 2014. 
75. ^ Jump up to: ^{a b} Seize the Daylight. p. 22. 
76. ^ Jump up to: ^{a b c d e f g} Brian Handwerk (December 1, 2013). "Time to Move On? The Case Against Daylight Saving Time". National Geographic News. Retrieved March 9, 2014. 
77. Jump up ^ "Daylight savings time". Session Weekly. Minnesota House Public Information Office. 1991. Retrieved August 7, 2013. ... the Minneapolis Star, Jan. 28, 1959 ... [stated] 'Farmers complained that they cannot get into the fields any earlier than under standard time ... because the morning sun does not dry the dew "on daylight savings time." '  
78. ^ Jump up to: ^{a b c} Parfitt, Tom (March 25, 2011). "Think of the cows: clocks go forward for the last time in Russia". The Guardian. Retrieved January 5, 2012. 
79. Jump up ^ Thomas C. Schelling (2006) [1972]. "Hockey helmets, daylight saving, and other binary choices" (PDF). Micromotives and Macrobehavior. W. W. Norton. ISBN 0-393-32946-1. 
80. Jump up ^ Daniel S. Hamermesh; Caitlin Knowles Myers; Mark L. Pocock (2008). "Cues for timing and coordination: latitude, Letterman, and longitude". Journal of Labor Economics. 26 (2): 223–246. doi:10.1086/525027. 
81. Jump up ^ Dilip R. Ahuja; D. P. Sen Gupta; V. K. Agrawal (2007). "Energy savings from advancing the Indian Standard Time by half an hour" (PDF). Current Science. 93 (3): 298–302. 
82. Jump up ^ Ryan Kellogg; Hendrik Wolff (2008). "Daylight time and energy: evidence from an Australian experiment". Journal of Environmental Economics and Management. 56 (3): 207–220. doi:10.1016/j.jeem.2008.02.003.  An earlier version is in: Ryan Kellogg; Hendrik Wolff (2007). "Does extending daylight saving time save energy? Evidence from an Australian experiment". CSEMWP 163. Center for the Study of Energy Markets. 
83. Jump up ^ "The facts on electricity consumption and daylight saving" (Press release). Western Power. October 31, 2007. 
84. Jump up ^ Wee-Kean Fong; Hiroshi Matsumoto; Yu-Fat Lun; Ryushi Kimura (2007). "Energy savings potential of the Summer Time concept in different regions of Japan from the perspective of household lighting". Journal of Asian Architecture and Building Engineering. 6 (2): 371–378. doi:10.3130/jaabe.6.371. 
85. Jump up ^ Yoshiyuki Shimoda; Takahiro Asahia; Ayako Taniguchia; Minoru Mizuno (2007). "Eval‎‎uation of city-scale impact of residential energy conservation measures using the detailed end-use simulation model". Energy. 32 (9): 1617–1633. doi:10.1016/j.energy.2007.01.007. 
86. Jump up ^ Adrienne Kandel; Margaret Sheridan (May 25, 2007). "The effect of early daylight saving time on California electricity consumption: a statistical analysis" (PDF). CEC-200-2007-004. California Energy Commission. 
87. Jump up ^ Brendan Cronin; Elizabeth Garnsey (October 19, 2007). "Daylight saving in GB; is there evidence in favour of clock time on GMT?" (PDF). Dept. of Engineering, University of Cambridge. Archived from the original (PDF) on February 16, 2008. 
88. Jump up ^ Brendan Cronin; Elizabeth Garnsey (October 20, 2009). "Daylight saving in GB; is there evidence in favour of clock time on GMT? (October 2009 revision)" (PDF). Dept. of Engineering, University of Cambridge. 
89. Jump up ^ Matthew J. Kotchen; Laura E. Grant (2008). "Does daylight saving time save energy? evidence from a natural experiment in Indiana" (PDF). NBER Working Paper No. 14429. National Bureau of Economic Research.  Lay summary: Wall Street Journal, February 27, 2008.
90. ^ Jump up to: ^{a b} David B. Belzer; Stanton W. Hadley; Shih-Miao Chin (2008). "Impact of Extended Daylight Saving Time on national energy consumption: report to Congress, Energy Policy Act of 2005, Section 110" (PDF). US Dept. of Energy. 
91. Jump up ^ Michael Downing (March 13, 2010). "Daylight saving: beat the clock". Huffington Post. 
92. Jump up ^ Dana Knight (April 17, 2006). "Daylight-saving time becomes daylight-spending time for many businesses". Indianapolis Star. 
93. Jump up ^ Spring Forward. pp. 147–148. 
94. Jump up ^ "Should we change the clocks?". National Farmers Union. Archived from the original on December 6, 2011. Retrieved January 6, 2012. 
95. Jump up ^ Fisher, Marc. "It's Time For Double Daylight Saving Time". Washington Post. Retrieved January 5, 2012. 
96. Jump up ^ "Single/Double Summer Time" (PDF). The Royal Society for the Prevention of Accidents. Retrieved January 5, 2012. 
97. Jump up ^ Todd D. Rakoff (2002). A Time for Every Purpose: Law and the Balance of Life. Harvard University Press. p. 26. ISBN 0-674-00910-X. 
98. Jump up ^ Ben Arnoldy (March 7, 2007). "Latest computer glitch: daylight saving time". Christian Science Monitor. 
99. Jump up ^ Mark J. Kamstra; Lisa A. Kramer; Maurice D. Levi (2000). "Losing sleep at the market: the daylight saving anomaly". American Economic Review. 90 (4): 1005–1011. doi:10.1257/aer.90.4.1005. 
100. Jump up ^ Luisa Müller; Dirk Schiereck; Marc W. Simpson; Christian Voigt (2009). "Daylight saving effect". Journal of Multinational Financial Management. 19 (2): 127–138. doi:10.1016/j.mulfin.2008.09.001. 
101. Jump up ^ Michael J. Pinegar (2002). "Losing sleep at the market: Comment". American Economic Review. 92 (4): 1251–1256. JSTOR 3083313. 
102. Jump up ^ Mark J. Kamstra; Lisa A. Kramer; Maurice D. Levi (2002). "Losing sleep at the market: the daylight saving anomaly: Reply". American Economic Review. 92 (4): 1257–1263. JSTOR 3083314. 
103. Jump up ^ Linda L. Lawson (May 24, 2001). "Statement to the U.S. House, Committee on Science, Subcommittee on Energy". Energy Conservation Potential of Extended and Double Daylight Saving Time. Serial 107-30. 
104. Jump up ^ Susan A. Ferguson; David F. Preusser; Adrian K. Lund; Paul L. Zador; Robert G. Ulmer (1995). "Daylight saving time and motor vehicle crashes: the reduction in pedestrian and vehicle occupant fatalities" (PDF). American Journal of Public Health. 85 (1): 92–95. doi:10.2105/AJPH.85.1.92. PMC 1615292. PMID 7832269. 
105. Jump up ^ Douglas Coate; Sara Markowitz (2003). "The effects of daylight and daylight saving time on US pedestrian fatalities and motor vehicle occupant fatalities". Accident Analysis & Prevention. 36 (3): 351–357. doi:10.1016/S0001-4575(03)00015-0. PMID 15003579. 
106. Jump up ^ J. Broughton; M. Stone (1998). "A new assessment of the likely effects on road accidents of adopting SDST". TRL368. Transport Research Laboratory. 
107. Jump up ^ Zurich Connect, ed. (October 26, 2009). "As the clocks go back, car accidents increase. Coincidence?". 
108. Jump up ^ Alex Vincent; Stanley Coren (1998). "Effects of daylight savings time on collision rates". New England Journal of Medicine (Full free text). 339 (16): 1167–1168. doi:10.1056/NEJM199810153391617. PMID 9776656.  Data supporting Coren's half of this exchange are in: Stanley Coren (1998). "Sleep deficit, fatal accidents, and the spring shift to daylight savings time". INABIS '98. 
109. Jump up ^ Clock shifts and accidents:
     • Jason Varughese; Richard P. Allen (2001). "Fatal accidents following changes in daylight savings time: the American experience". Sleep Medicine. 2 (1): 31–36. doi:10.1016/S1389-9457(00)00032-0. PMID 11152980. 
     • J. Alsousoua; T. Jenks; O. Bouamra; F. Lecky; K. Willett (2009). "Daylight savings time (DST) transition: the effect on serious or fatal road traffic collision related injuries". Injury Extra. 40 (10): 211–2. doi:10.1016/j.injury.2009.06.241. 
     • Tuuli A. Lahti; Jari Haukka; Jouko Lönnqvist; Timo Partonen (2008). "Daylight saving time transitions and hospital treatments due to accidents or manic episodes". BMC Public Health. 8: 74. doi:10.1186/1471-2458-8-74. PMC 2266740. PMID 18302734. 
     • Mats Lambe; Peter Cummings (2000). "The shift to and from daylight savings time and motor vehicle crashes". Accident Analysis & Prevention. 32 (4): 609–611. doi:10.1016/S0001-4575(99)00088-3. PMID 10868764. 
110. Jump up ^ Christopher M. Barnes; David T. Wagner (2009). "Changing to daylight saving time cuts into sleep and increases workplace injuries" (PDF). Journal of Applied Psychology. 94 (5): 1305–1317. doi:10.1037/a0015320. PMID 19702372. 
111. Jump up ^ House Committee on Energy and Commerce, Subcommittee on Energy Conservation and Power (April 24, 1985). Daylight saving time. Serial No. 99-4. U.S. GPO. p. 26. 
112. Jump up ^ Rachel Pain; Robert MacFarlane; Keith Turner; Sally Gill (2006). "'When, where, if, and but': qualifying GIS and the effect of streetlighting on crime and fear". Environment and Planning A. 38 (11): 2055–2074. doi:10.1068/a38391. 
113. Jump up ^ Clock shifts as safety reminders:
     • "Smoke alarms a burning issue". East and Bays Courier. New Zealand. April 4, 2008. 
     • "CSPC and USFA encourage consumers to spring forward with fire safety in mind" (Press release). U.S. Consumer Product Safety Commission; U.S. Fire Administration. March 9, 2007. 
     • "Get ready: set your clocks, check your stocks". American Public Health Association. February 24, 2009. 
114. Jump up ^ Debby Golonka (February 26, 2009). "Prevent household fires". Healthwise. 
115. Jump up ^ Sualeh Fatehi (2015). "Daylight Chart". 
116. Jump up ^ Michael Rosenberg; Lisa Wood (2010). "The power of policy to influence behaviour change: daylight saving and its effect on physical activity". Australian and New Zealand Journal of Public Health. 34 (1): 83–88. doi:10.1111/j.1753-6405.2010.00479.x. 
117. Jump up ^ A.V. Parisi; J. Turner; D.J. Turnbull; P. Schouten; N. Downs (2008). "Influence of summer daylight saving time on scattered erythemal solar ultraviolet exposures". Journal of Photochemistry and Photobiology B: Biology. 91 (1): 35–40. doi:10.1016/j.jphotobiol.2008.01.010. PMID 18321724. 
118. Jump up ^ Henry Olders (2003). "Average sunrise time predicts depression preval‎‎ence". Journal of Psychosomatic Research. 55 (2): 99–105. doi:10.1016/S0022-3999(02)00479-8. PMID 12932507. 
119. Jump up ^ Shari Roan (March 5, 2007). "Change in daylight saving time may affect moods". Los Angeles Times. 
120. Jump up ^ Sipilä, JO; Ruuskanen, JO; Rautava, P; Kytö, V (undefined NaN). "Changes in ischemic stroke occurrence following daylight saving time transitions.". Sleep Medicine. 27-28: 20–24. PMID 27938913.  Check date values in: |date= (help)
121. Jump up ^ DST and circadian rhythm:
     • Pablo Valdez; Candelaria Ramírez; Aída García (2003). "Adjustment of the sleep–wake cycle to small (1–2h) changes in schedule". Biological Rhythm Research. 34 (2): 145–155. doi:10.1076/brhm.34.2.145.14494. 
     • Thomas Kantermann; Myriam Juda; Martha Merrow; Till Roenneberg (2007). "The human circadian clock's seasonal adjustment is disrupted by daylight saving time". Current Biology. 17 (22): 1996–2000. doi:10.1016/j.cub.2007.10.025. PMID 17964164. Lay summary – ABC Science Online, Australia (2007-10-25).  CS1 maint: Multiple names: authors list (link)
122. Jump up ^ Michael Berk; Seetal Dodd; Karen Hallam; Lesley Berk; John Gleeson; Margaret Henry (2008). "Small shifts in diurnal rhythms are associated with an increase in suicide: the effect of daylight saving". Sleep and Biological Rhythms. 6 (1): 22–25. doi:10.1111/j.1479-8425.2007.00331.x. 
123. Jump up ^ Imre Janszky; Rickard Ljung (2008). "Shifts to and from daylight saving time and incidence of myocardial infarction". New England Journal of Medicine. 359 (18): 1966–1968. doi:10.1056/NEJMc0807104. PMID 18971502. Lay summary – Los Angeles Times (2008-10-30). 
124. Jump up ^ Nataliya Shirinskikh, translator (March 16, 2005). "Kazakhstan canceled shifting to the 'summer' and 'winter' time". Kazakhstan Today. 
125. Jump up ^ "Russian clocks stay on summertime". BBC News. 
126. Jump up ^ Int Panis, L; Beckx, C (2007). "TRUCKS DRIVING AT NIGHT AND THEIR EFFECT ON LOCAL AIR POLLUTION". European Transport Conference. 
127. Jump up ^ Joey Crandall (October 24, 2003). "Daylight saving time ends Sunday". Record–Courier. Archived from the original on February 29, 2012. 
128. Jump up ^ Paul McDougall (March 1, 2007). "PG&E says patching meters for an early daylight-saving time will cost $38 million". InformationWeek. 
129. Jump up ^ "Daylight saving time: rationale and original idea". 2008. ... Lord Balfour came forward with a unique concern: 'Supposing some unfortunate lady was confined with twins ...' 
130. Jump up ^ Daniel G. Schultz (March 29, 2007). "Unpredictable events in medical equipment due to new daylight saving time change". Center for Devices and Radiological Health, Food and Drug Administration. 
131. Jump up ^ Jesse Ruderman (November 1, 2006). "Continuous daylight saving time". 
132. Jump up ^ "Proposal for a finer adjustment of summer time (daylight saving time)". September 28, 2011. 
133. Jump up ^ Albert E. Waugh (1973). Sundials: Their Theory and Construction. Dover. ISBN 0-486-22947-5. 
134. Jump up ^ Leith Holloway (1992). "Atmospheric sun protection factor on clear days: its observed dependence on solar zenith angle and its relevance to the shadow guideline for sun protection". Photochemistry and Photobiology. 56 (2): 229–34. doi:10.1111/j.1751-1097.1992.tb02151.x. PMID 1502267. 
135. Jump up ^ Seize the Daylight. p. xv. 
136. Jump up ^ Daylight saving time and its variants:
     • Richard A. Meade (1978). "Language change in this century". English Journal. 67 (9): 27. doi:10.2307/815124. 
     • Joseph P. Pickett; et al., eds. (2000). "daylight-saving time". The American Heritage Dictionary of the English Language (4th ed.). Boston: Houghton Mifflin. ISBN 0-395-82517-2. or daylight-savings time  CS1 maint: Explicit use of et al. (link)
     • "daylight saving time". Merriam–Webster's Online Dictionary. Retrieved February 13, 2009. called also daylight saving, daylight savings, daylight savings time, daylight time 
     • Oxford Dictionaries "also daylight savings time"
     • "15 U.S.C. § 260a notes". Retrieved May 9, 2007. Congressional Findings; Expansion of Daylight Saving Time 
137. Jump up ^ Steve Lohr (March 5, 2007). "Time change a 'mini-Y2K' in tech terms". New York Times. 
138. Jump up ^ A. Gut; L. Miclea; Sz. Enyedi; M. Abrudean; I. Hoka (2006). "Database globalization in enterprise applications". 2006 IEEE International Conference on Automation, Quality and Testing, Robotics. pp. 356–359. 
139. Jump up ^ Ron Bean (November 2000). "The Clock Mini-HOWTO". 
140. Jump up ^ Raymond Chen (November 2000). "Why does Windows keep your BIOS clock on local time?". 
141. Jump up ^ Paul Eggert; Arthur David Olson (June 30, 2008). "Sources for time zone and daylight saving time data". 
142. Jump up ^ "tztab(4)" (PDF). HP-UX Reference: HP-UX 11i Version 3. Hewlett–Packard Co. 2010. 
143. Jump up ^ "Other environment variables". IEEE Std 1003.1–2004. The Open Group. 2004. 
144. Jump up ^ "Daylight saving time help and support center". Microsoft Corp. September 14, 2007. 
145. Jump up ^ "Visual Studio and daylight saving time change". Microsoft Corp. 2007. Archived from the original on August 31, 2012. 
146. Jump up ^ "Windows daylight savings timezones for Israel". Lingnu Open Source Consulting. 2009. 
147. Jump up ^ "Microsoft support entry regarding daylight saving time in Israel" (in Hebrew). Microsoft Corp. 2007. Archived from the original on November 3, 2013. 
148. Jump up ^ Harkov, Lahav (July 8, 2013). "Knesset votes to extend Daylight Saving Time". Jerusalem Post. Jerusalem. Retrieved October 20, 2016. 
149. Jump up ^ Markus Kuhn (February 10, 2009). "IBM PC Real Time Clock should run in UT". Computer Laboratory, University of Cambridge. 
150. Jump up ^ Microsoft. "You cannot change system time if RealTimeIsUniversal registry entry is enabled in Windows". 
151. Jump up ^ Microsoft. "High CPU usage during DST changeover in Windows Server 2008, Windows 7, or Windows Server 2008 R2". 
152. Jump up ^ "Chile keeps Daylight time". January 28, 2015. 
153. Jump up ^ "Russia set to turn back the clocks with daylight-saving time shift". The Guardian. July 1, 2014. Retrieved October 25, 2014. 

Further reading[edit]

• Ian R. Bartky (2007). One Time Fits All: The Campaigns for Global Uniformity. Stanford University Press. ISBN 978-0-8047-5642-6. 
• Ian R. Bartky; Elizabeth Harrison (1979). "Standard and daylight-saving time". Scientific American. 240 (5): 46–53. doi:10.1038/scientificamerican0579-46. ISSN 0036-8733. 
• Michael Downing (2005). Spring Forward: The Annual Madness of Daylight Saving Time. Shoemaker & Hoard. ISBN 1-59376-053-1. 
• David Prerau (2005). Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time. Thunder's Mouth Press. ISBN 1-56025-655-9.  The British version, focusing on the UK, is Saving the Daylight: Why We Put the Clocks Forward. Granta Books. ISBN 1-86207-796-7. 

External links[edit]

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• "Legal Time 2015", Telecommunications Standardization Bureau of the ITU
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• Sources for time zone and daylight saving time data

[show] v t e Time measurement and standards
Chronometry Orders of magnitude Metrology
International standards	UTC UTC offset UT ΔT DUT1 IERS ISO 31-1 ISO 8601 TAI 12-hour clock 24-hour clock Barycentric Coordinate Time Barycentric Dynamical Time Civil time Daylight saving time Geocentric Coordinate Time International Date Line Leap second Solar time Terrestrial Time Time zone
Obsolete standards	Ephemeris time Greenwich Mean Time Prime meridian
Time in physics	Absolute time and space Spacetime Chronon Continuous time Coordinate time Cosmological decade Discrete time Planck epoch Planck time Proper time Theory of relativity Time dilation Gravitational time dilation Time domain T-symmetry
Horology	Clock Astrarium Atomic clock Complication History of timekeeping devices Hourglass Marine chronometer Marine sandglass Radio clock Watch Water clock Sundial Dialing scales Equation of time History of sundials Sundial markup schema
Calendar	Astronomical Dominical letter Epact Equinox Gregorian Hebrew Hindu Intercalation Islamic Julian Leap year Lunar Lunisolar Solar Solstice Tropical year Weekday determination Weekday names
Archaeology and geology	Chronological dating Dating methodologies in archaeology Geologic time scale International Commission on Stratigraphy
Astronomical chronology	Galactic year Nuclear timescale Precession Sidereal time
Units of time	Century Day Decade Fortnight Hour Jiffy Lustrum Millennium Minute Moment Month Paksha Saeculum Second Shake Tide Week Year
Related topics	Chronology Duration music Mental chronometry Metric time System time Time value of money Timekeeper

[show]

• v
• t
• e

Coordinated Universal Time (UTC)

UTC offset for standard time and
Daylight saving time (DST)
Italics: historical or unofficial

180° to < 90°W	−12:00 −11:00 −10:30 −10:00 −09:30 −09:00 −08:30 −08:00 −07:00
90°W to < 0°	−06:00 −05:00 −04:30 −04:00 −03:30 −03:00 −02:30 −02:00 −01:00 −00:44 −00:25:21
0° to < 90°E	±00:00 +00:20 +00:30 +01:00 +01:24 +01:30 +02:00 +02:30 +03:00 +03:30 +04:00 +04:30 +04:51 +05:00 +05:30 +05:40 +05:45
90°E to < 180°	+06:00 +06:30 +07:00 +07:20 +07:30 +08:00 +08:30 +08:45 +09:00 +09:30 +09:45 +10:00 +10:30 +11:00 +11:30
(180° to < 90°W)	+12:00 +12:45 +13:00 +13:45 +14:00

Time zone data sources

tz database

Lists of time zones

• Time zones by country
• Time zones by UTC offset
• tz database time zones
• Military time zones
• Time zone abbreviations
• Daylight saving time by country

[show] v t e Daylight saving time (or summer time)
By continent	Daylight saving time in Africa Daylight saving time in Asia Daylight saving time in the Americas Summer Time in Europe Daylight saving time in Oceania
Overviews	Daylight saving time by country

Authority control	NDL: 00570171

Retrieved from "https://en.wikipedia.org/w/index.php?title=Daylight_saving_time&oldid=765082975"

Categories:

• Daylight saving time
  

■ 2017년 11월 5일(음력 9월 24일) CANADA Daylight Saving Time Ends(11월 첫번째 일요일)

11월 첫째 주 일요일 오전 2시에 시계를 1시로 조정하면 된다.

한국과 캐나다의 시차는 16시간에서 17시간으로 늘어난다.  

캐나다의 일광절약시간제(Daylight Saving Time)(써머타임제)는 매년 3월 둘째 주 일요일에 시작(오전 2시를 3시로)되어 11월 첫째 주 일요일에 해제(오전 2시를 1시로)된다.  

일광절약시간제는 해가 일찍 뜨는 하절기에 시간을 한 시간씩 앞당기는 제도다. 일조 시간을 최대한 활용해 전기 에너지 소모를 줄이고, 시간을 효율적으로 사용하기 위해 도입됐다.

■  Living Information - http://cafe.daum.net/mundypark1/EiHd/1