Saturday night—or to be more precise, Sunday at 2 a.m.—marks the end of daylight saving time. Per the "spring forward, fall back" saying, everyone should turn their clocks back an hour today.
The National Fire Protection Association and the U.S. Consumer Product Safety Commission both recommend that people change the batteries in their smoke and carbon monoxide detectors on the same day they change their clocks for daylight saving time.
Homeowners should also recycle the batteries instead of throwing them in the trash, which is illegal in California. Residents should contact their respective waste haulers or city halls for information on battery drop-off locations.
The California Energy Commission recommends that people also use the opportunity to change at least one incandescent light bulb to an energy-saving compact fluorescent bulb.
Daylight saving time begins at 2 a.m. on the second Sunday in March and lasts until the first Sunday in November, according to the California Energy Commission. Most of Arizona, Hawaii, American Samoa, Guam, Puerto Rico and the Virgin Islands do not observe daylight saving time.
For years, authorities maintained that daylight saving time saved electricity; at one point during the energy crisis, California considered moving to an earlier daylight saving time or staying on daylight saving time year-round.
Nevertheless, more recent studies have concluded that the amount of energy saved is marginal, and one even concluded that daylight saving time increased residential electricity demand.
Editor's note: A version of this article was originally published Nov. 5, 2011.