Daylight-saving time begins at 2 a.m. Sun., March 11. The time change previously began on the first Sunday in April, but has been moved forward three weeks on the calendar in an effort to save more energy.

The return to standard time has changed, too. Normally daylight-saving time ends on the last Sunday in October. This year clocks will be changed a week later, at 2 a.m. Sun., Nov. 4.

Clocks move forward in spring and fall back in autumn.

Daylightsaving time is notobserved in Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands, and by most of Arizona.