For Joyce Swain, daylight-saving time means enjoying the outdoors well into early evening.

"My mornings also seem to go better," said Swain, of Port Hueneme, Calif.

Swain and millions of other Americans will have to turn their clocks forward by an hour this weekend. Daylight-saving time starts at 2 a.m. Sunday.

Supporters of the time shift say it brings numerous benefits, including more time to exercise outdoors and meet others after work.

But one long-touted benefit — that daylight-saving time reduces energy use — might not be true.

A study published last month by a University of California-Santa Barbara economics professor and a graduate student found that residential energy use in Indiana went up by 1 percent to 4 percent during daylight-saving time.

Laura Grant, a doctorate student at UCSB's Bren School of Environmental Science and Management, said Indiana provided her and economics professor Matthew Kotchen with an opportunity to test whether daylight-saving time actually reduces energy use.

Until 2006, only 15 of Indiana's 92 counties were on daylight-saving time. Most rural counties chose to stay on standard time, partly because farmers objected to an extra hour of morning darkness. But a law mandating daylight-saving time for all counties took effect in 2006.

Grant and Kotchen compared monthly meter readings of electricity consumption provided by Duke Energy Corp. for millions of households across Indiana before and after daylight-saving time was implemented statewide.

The readings showed that electricity use "actually went up during the warmer months, when daylight-saving time was in place," compared with earlier years when it was not, Grant said. The study found daylight-saving time cost Indiana households $8.6 million more in electricity annually.

While daylight-saving time might have reduced lighting needs, "those savings were more than offset by having to turn on the heat during the colder early morning hours," especially at the beginning and end of daylight-saving time, Grant said.

And during the summer, many people turned on their air conditioners when they came home from work an hour earlier and it was still hot, Grant said.

Benjamin Franklin proposed turning clocks forward in the spring and back in the fall after noticing that people were sleeping through the sunlit early-morning hours of spring and summer, Grant said. They were also using candles for light in the evening.

Franklin saw that a lot of wax could be saved by moving the clock forward during spring and summer, but modern appliances such as air conditioners have changed the equation, Grant said.

A recent study by the California Energy Commission also could not find any clear evidence of energy savings from daylight-saving time.

Despite the studies, daylight-saving time does provide consumers with the chance for other energy savings, said Cheryl Collart, executive director of the Ventura County Regional Energy Alliance.

"One of the best things you can do is reset any timers you may have in your home, so you're not wasting energy during the longer daylight hours," Collart said.