Daylight Savings Begins: 5 Facts You May Not Have Known

Clocks will "spring forward" an hour at 2 a.m. Sunday, March 9, for daylight savings time.

Besides adjusting clocks, fire departments are reminding people to check and replace smoke alarm batteries at the beginning of daylight saving time.

Here are five little known facts about daylight savings time, according to ABC News.

1. Daylight Saving Time Was Conceived as a Way to Save Energy
In the U.S., daylight saving time was first used during World War I to conserve resources. It was reinstated again during World War II until Sept. 1945. The Uniform Time Act of 1966 created a standardized system to observe daylight saving time. 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.

2. Daylight Saving Time Begins in March and Ends in November From World War II until recently, the seven-month period of daylight saving time in the U.S. ran from April until mid-October. But 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 the need to turn on lights in homes at night.

3. Not All US States and Territories Observe Daylight Saving Time
The majority of the U.S. loses an hour of sleep when the time switch occurs. With the exception of the Navajo Nation in the northeastern part of the state, Arizona has not been moving their clocks forward like the rest of the country each spring. According to an Arizona Republic editorial in 1969, the reasoning behind not springing forward was due to the heat. Aside from Arizona, Hawaii, American Samoa, Guam, Puerto Rico, Northern Marianas and the Virgin Islands do not move their clocks forward.

4. Daylight Saving Time Helps Prevent Traffic Injuries and Reduces Crime
The extra hour of daylight has been credited for preventing traffic injuries and reducing crime as "people travel to and from school and work and complete errands during the daylight," and "more people are out conducting their affairs during the daylight rather than at night, when more crime occurs," according to the U.S. Department of Transportation.

5. Time Changes Can Impact Body
It's just one hour but the time shift and stress caused by time changes can be bad for the body. Researchers in Sweden reported in 2008 in the New England Journal of Medicine that the number of heart attacks jumps during the period immediately following time changes, and that those vulnerable to sleep deprivation should be extra careful. "More than 1.5 billion men and women are exposed to the transitions involved in daylight saving time: turning clocks forward by an hour in the spring and backward by an hour in the autumn," wrote Imre Janszky and Rickard Ljung, health and welfare researchers in Sweden. "These transitions can disrupt chronobiologic rhythms and influence the duration and quality of sleep, and the effect lasts for several days after the shifts."

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