Are you ready for an extra hour of sleep? You’ll get one this Sunday, November 1, when we set our clocks back an hour and go off Daylight Saving Time at 2 a.m. This gives us back the hour we lost on March 8.

Not all places in the U.S. observe daylight time. In particular, Hawaii and most of Arizona do not use it. Daylight Saving Time has always been a topic of debate, and was first established in 1918, according to the U.S. Naval Observatory.

Although standard time in time zones was instituted in the U.S. and Canada by the railroads in 1883, it was not established in U.S. law until the Act of March 19, 1918, sometimes called the Standard Time Act. The act also established daylight saving time, a contentious idea then. Daylight saving time was repealed in 1919, but standard time in time zones remained in law. Daylight time became a local matter. It was re-established early in World War II, and was continuously observed from February 9, 1942 to September 30, 1945. After the war, its use varied among states and localities. The Uniform Time Act of 1966 provided standardization in the dates of beginning and end of daylight time in the U.S. but allowed for local exemptions from its observance. The act provided that daylight time begin on the last Sunday in April and end on the last Sunday in October, with the changeover to occur at 2 a.m. local time.

During the “energy crisis” years, Congress enacted earlier starting dates for daylight time. In 1974, daylight time began on January 6 and in 1975 it began on February 23. After those two years, the starting date reverted back to the last Sunday in April. In 1986, a law was passed that shifted the starting date of daylight time to the first Sunday in April, beginning in 1987. The ending date of daylight time was not subject to such changes, and remained the last Sunday in October. The Energy Policy Act of 2005 changed both the starting and ending dates. Beginning in 2007, daylight time starts on the second Sunday in March and ends on the first Sunday in November.