Saturday, Oct. 31, 2009 | 2:10 a.m.
Most of the United States, including Las Vegas, will gain an hour at 2 a.m. Sunday by turning back clocks to standard time.
When daylight saving time began at 2 a.m. on March 8, clocks sprang forward one hour.
Why change time at 2 a.m.? When daylight saving time began in Great Britain and then the United States in the 19th century, early morning was a perfect time with less disruption to the railroads.
Benjamin Franklin proposed daylight saving time as an American delegate in Paris in 1784. The idea caught on to standardize time in London in 1840, proposed by the railroads there. The United States followed on Nov. 18, 1883, again led by the railroads.
While most states observe the spring forward, fall back switch in time, Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands, the Commonwealth of Northern Mariana Islands and Arizona do not change the clock.
However, the Navajo Nation in Arizona does participate in daylight saving time and will roll the clock back Sunday. The Hopi Reservation, entirely surrounded by the Navajo Nation, does not observe daylight saving time, creating a "doughnut hole" in time in the middle of Arizona.
In 2007, Congress voted to switch the end of daylight saving time to the first Sunday in November to offer trick-or-treaters more daylight time to venture into the streets, although most children wait until after dark to go out.
Las Vegas Fire Department spokesman Tim Szymanski said the return to standard time is perfect for changing batteries in smoke detectors.
Until March 14, 2010, when the United States springs forward an hour for daylight saving time, most Americans can enjoy an extra hour of sleep Sunday morning.