Daylight Saving Time Begins Sunday

Once again, the old calendar on the wall says it's time to change the clock, trading an hour's sleep for more evening sunshine.

Most Americans will set their clocks forward one hour this weekend.

Officially, the change to daylight saving time occurs at 2 a.m. Sunday, local time, though most people will reset their clocks and watches before going to bed.

The shift also serves as a reminder to install new batteries in warning devices such as smoke detectors and hazard warning radios.

The change to daylight saving time allows people to use less energy to light their homes by taking advantage of the longer and later daylight hours.

In areas that observe the change, standard time will return on Nov. 1.

Daylight saving time became longer with the passage of the Energy Policy Act in 2005, which extended DST by four weeks from the second Sunday of March to the first Sunday of November.

Modern DST was first proposed in 1907 by William Willett of the United Kingdom who wrote in his pamphlet, "The Waste of Daylight," that clocks should be advanced by 80 minutes in the summer.

The outbreak of World War I increased the importance of the issue, mostly because of the need to save coal.

A daylight plan was adopted in the United States in 1918, setting summer DST to begin on March 31 of that year. It also established standard time zones.

A federal law wasn't passed until much later. The Uniform Time Act of 1966 officially established "daylight time" in the United States. The law does not require any area to observe daylight saving time, but if a state chooses to do so, it must follow the starting and ending dates set by the law.

Parts of the country that don't observe daylight saving time include Arizona, Hawaii, Puerto Rico, the Virgin Islands, American Samoa, Guam and the Northern Marianas. The main reason is that areas closer to the equator have days that are more consistent in length throughout the year.

More than one billion people in about 70 countries around the world observe DST in some form.