Most people in the United States are getting an extra hour of sleep this weekend, thanks to the annual shift back to standard time.

Officially, the change comes at 2 a.m. Sunday, but most people set their clocks back before heading to bed Saturday night.

Residents of Hawaii, most of Arizona and some U.S. territories don't have to change; daylight saving time is not observed there.

Public safety officials say this is a good time to put a new battery in the smoke alarm no matter where you live.

Daylight saving time returns at 2 a.m. local time the second Sunday in March — March 8, 2015.