Facts about Daylight Saving Time

The daylight saving time begins at 2:00am on the second Sunday in March and changes back to standard time on the first Sunday in November. That means, in spring, clock jumps from 1:59am to 3:00am and falls back from 1:59am to 1:00am. So we miss one hour and gain one hour, respectively. One funny thing is that no one was born at 2:00am on the second Sunday in March in the US.

Some interesting facts about the daylight saving time.

1. EU also has daylight saving time, which begins and ends at 1:00am GMT in the last Sunday in March and the last Sunday in October. All time zones in EU change at the same moment.

2. Daylight saving time has unintended health consequences because physical clock movement interfere with the body's internal clock, so called circadian rhythm uses daylight to stay in tune with environment. Our body clock remains unadjusted. Studies found that in spring, the body clock is more in tuned with the physical clock. Such clock changes can cause restlessness and sleep disruption.

3. Not all US states observe daylight saving time. Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands, the Commonwealth of Northern Mariana Islands, and Arizona don't have daylight saving time. The Navajo Nation participates in the Daylight Saving Time policy, even in Arizona, due to its large size and location in three states.

4. To keep to their published timetables, trains cannot leave a station before the scheduled time. So, when the clocks fall back one hour in October, all Amtrak trains in the U.S. that are running on time stop at 2:00 a.m. and wait one hour before resuming. Overnight passengers are often surprised to find their train at a dead stop and their travel time an hour longer than expected. At the spring Daylight Saving Time change, trains instantaneously become an hour behind schedule at 2:00 a.m., but they just keep going and do their best to make up the time.

5. An formal reason of having daylight saving time is to save energy. Reports in 1975 by the Department of Transportation showed that there was about 1% electricity reduction after using DST. But surveys said people like it for other reasons. Mainly, it is because they like to have longer evening and can do more.

6. Efficiency of DST has been debated for a long time to see how clock shifting can actually save energy. People behavioral pattern would also change along with DST. Some studies found that DST actually causes more electricity in 2005.

7. The idea of daylight saving was first conceived by Benjamin Franklin during his sojourn as an American delegate in Paris in 1784, in an essay, "An Economical Project".

8. Daylight Saving Time has been used in the U.S. and in many European countries since World War I. At that time, in an effort to conserve fuel needed to produce electric power, Germany and Austria took time by the forelock, and began saving daylight at 11:00 p.m. on April 30, 1916, by advancing the hands of the clock one hour until the following October. Other countries immediately adopted this 1916 action: Belgium, Denmark, France, Italy, Luxembourg, Netherlands, Norway, Portugal, Sweden, Turkey, and Tasmania. Nova Scotia and Manitoba adopted it as well, with Britain following suit three weeks later, on May 21, 1916. In 1917, Australia and Newfoundland began saving daylight.

9. The US had an inconsistent adoption of DST. In 1960s, there was no law stating clearly when to change the clocks. The law was not passed until 1986.

10. Equatorial and tropical countries (lower latitudes) generally do not observe Daylight Saving Time. Since the daylight hours are similar during every season, there is no advantage to moving clocks forward during the summer. China had observed summer Daylight Saving Time from 1986 through 1991; they do not observe DST now.