Welcome spring weather with the start of Daylight Saving Time.
At 2 a.m. on, Sunday, March 11, 2012, most U.S. residents will set their clocks ahead one hour for the beginning of Daylight Saving Time.
However, not all states will observe the time change. Residents of Arizona, Hawaii and U.S. territories Puerto Rico and the Virgin Islands will remain on their normal schedules.
About 75 countries and territories have at least one location that observes Daylight Saving Time, according to TimeandDate.com. Conversely, 164 don't observe the time change at all.
Daylight Saving Time gives way to longer days, but some won't be too delighted to lose an hour of sleep. In fact, some scientists suggest the 'spring-forward" time change disrupts sleep and could pose health risks, such as heart attacks.
Benjamin Franklin has been credited with the idea of Daylight Saving Time, but Britain and Germany began using the concept in World War I to conserve energy, the Washington Post observes. The U.S. used Daylight Saving Time for a brief time during the war, but it didn't become widely accepted in the States until after the second World War.
In 1966, the Uniform Time Act outlined that clocks should be set forward on the last Sunday in April and set back the last Sunday in October.
That law was amended in 1986 to start daylight saving time on the first Sunday in April, though the new system wasn't implemented until 1987. The end date was not changed, however, and remained the last Sunday in October until 2006
Today, Daylight Saving Time begins on the second Sunday in March and ends on the first Sunday in November. The time change will precede the first day of spring and the vernal equinox, which is set to take place at 1:14 a.m. EDT on Tuesday, March 20.
Not a fan of Daylight Saving Time? Don't worry: You can resume your normal schedule on Nov. 4.
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