It’s time to “fall back” again this weekend and to set your clocks back one hour when you go to bed tonight.
Daylight saving time ends for most of the country, as standard time officially begins at 2 a.m. Sunday morning.
The seven-month period of daylight saving time is mandated by governments, which began implementing the time switch during World Wars I and II to save energy and resources for the war effort.
From World War II until recently, daylight saving in the U.S. ran from April until mid-October.
In 2007, Congress adjusted daylight saving time to begin three weeks earlier and end one week later — a move they hoped would help save energy.
At the time, they pointed to the fact that longer daylight in the evening hours reduced people’s need to turn on lights in their homes at night.
Critics of the policy questioned the government’s decision, wondering whether people would simply turn on as many lights in the morning hours instead.
In response, the Department of Energy studied the energy savings in 2008. They found that during daylight saving time, U.S. electricity use decreased by 0.5 percent per day, which added up to 1.3 billion kilowatt-hours, enough to power about 122,000 average U.S. homes for a year.