Clocks Go Back This Weekend: Here's When and Why

Most of the United States gets an extra hour of sleep this weekend. Daylight saving time ends at 2 a.m. local time on Sunday, November 1, when clocks roll back to 1 a.m. Smartphones and computers usually adjust on their own, but microwaves, car dashboards, and wall clocks often need a manual change.

The date is set by federal law. Under the Energy Policy Act of 2005, daylight saving time starts on the second Sunday in March and ends on the first Sunday in November. Hawaii and most of Arizona skip the change entirely, and US territories such as Puerto Rico stay on standard time all year.

The practice is older than many people assume. Germany adopted daylight saving time in 1916 to save fuel during World War I, and the United States followed in 1918. Congress set a national framework with the Uniform Time Act of 1966. Supporters argue that longer evenings encourage outdoor activity and spending. Critics point to studies showing that the energy savings are small or inconsistent, and to research linking the clock changes to sleep disruption and a temporary rise in traffic accidents.

Europe has already made the switch. European clocks went back on October 25, so travelers flying between the US and Europe may notice that the time gap has shifted for a few weeks.

For most people, the practical advice is simple. Check any devices that do not update automatically, and expect darker evenings for the next several months.