Daylight Saving Time is upon us: Which way to move the clocks?

Though swaths of the US are still locked in winter's grip of cold and snow, the time has come for an annual rite of spring: daylight saving.

Daylight Saving Time takes place at 2 a.m. Sunday, when for most of the United States time officially jumps forward an hour to 3 a.m. Exempt from clock-adjusting are Hawaii, Puerto Rico, the Virgin Islands, American Samoa, Guam, and the Northern Marianas Islands. Arizona is the only state that opts out voluntarily.

The federal government does not mandate Daylight Saving Time; states do. In some states, in fact, half the state adopts Daylight Saving Time and the other half does not. As many as 30 bills appear each year in state legislatures in favor either of halting it altogether or of adopting it all year long, Michael Downing, author of "Spring Forward: The Annual Madness of Daylight Saving Time," told the National Geographic Thursday.

Russia, Japan, and most African and Asian countries abolished Daylight Saving Time long ago, while most European and North American countries have not.

The time change dates from the Industrial Revolution, when workers' shifts and transportation schedules depended on having daylight to operate. The time shift is also traditionally thought to boost energy savings by reducing reliance on electricity for artificial light. Saving energy was Congress's intent in 2005 when it moved Daylight Saving Time from April to March, expecting a 1 percent drop in US consumption. (Congress does set a uniform time to begin and end Daylight Saving Time, for states that are making the shift.) 

Energy researchers are starting to dispute that energy-saving claim. According to a 2007 study by the University of California Energy Institute in Berkeley, Calif., households that on standard time would use lights longer in the evening ended up shifting their use to other times of day while on Daylight Saving Time (such as morning, when it's dark but people are up). 

Other research showing no energy savings from Daylight Saving Time compared places in Australia that were on standard time with Sydney, which had shifted to Daylight Savings Time two months early for the Olympic Games. Arguments to extend daylight because it will help energy efficiency “are at best overstated, and at worst carry the wrong sign … this study raises concern that the US is unlikely to see the anticipated energy conservation benefits,” researchers wrote.

Another study, in 2008 on household energy use in southern Indiana, found similar results. There, electricity consumption jumped between 2 and 4 percent for the two years after Indiana instituted statewide daylight saving. The reason: increased demand for lighting, heating, and cooling, depending on the month.

Writing in The New York Times Thursday, Matthrew Kotchen, an economics professor at Yale University who co-authored the study for the National Bureau of Economic Research in Cambridge, Mass., said, “the consequence for Indiana has been higher electricity bills and more pollution from power plants.”

“There are certainly benefits, but energy savings is not one of them – a tradeoff to acknowledge as we enjoy an extra hour of sunlight on those long summer evenings,” Professor Kotchen wrote.