Before climbing into bed Saturday night, don’t forget to set household clocks, wristwatches and vehicle clocks back an hour to avoid confusion the next morning.

Sunday, Nov. 7, signals the end of daylight saving time and the resumption of standard time. This year, daylight saving time officially ends Sunday at 2 a.m., but most people will turn clocks back before going to sleep Saturday night, Nov. 6.

That is, unless they live in Hawaii or Arizona, two states that do not observe daylight saving time.

According to the U.S. Naval Observatory, daylight saving time was established in U.S. law in 1918, and went through a succession of repeals and re-establishments until the enactment of the Uniform Time Act of 1966. This statute standardized the observation dates, providing an allowance for local exemptions.

During the “energy crisis” years of the mid-1970s, according to the U.S. Naval Observatory, Congress enacted earlier starting dates for daylight saving time. Decades later, the Energy Policy Act of 2005 changed both the starting and ending dates. Since 2007, daylight saving time has started on the second Sunday in March and ended on the first Sunday in November.