It's time to "spring ahead" - and lose an hour of shut-eye.
This weekend most of the U.S. makes the switch to Daylight Savings Time, moving clocks ahead one hour in order to ensure an extra hour of sunlight each evening.
The official change is at 2 a.m. local time on Sunday, March 13, 2011.
Not everyone in the U.S. makes the switch from standard time.
The exceptions are Hawaii, most of Arizona, Puerto Rico, the Virgin Islands, American Samoa, Guam and the Northern Marianas.
On November 6 you'll switch your clocks from 2 a.m. to 1 a.m. and get your lost hour of sleep back - unless you spend the extra hour celebrating the return of Standard Time.
For more info:
Daylight Saving Time Rules (National Institute of Standards and Technology)