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How Daylight Saving Time Works


Don't Touch That Clock! Arguments Against Daylight Saving Time

Over the years, many well-known politicians have fiercely championed daylight saving time. U.S. President Warren G. Harding, however, despised it, despite being an avid golfer and a fan of Major League Baseball. In 1922, he made daylight saving time voluntary for private employers but not federal ones in the District of Columbia. Some institutions and businesses shifted their clocks, while others didn't. As a result, the city was thrown into chaos, and the experiment was eventually terminated [source: Fisher].

During Harding's misguided DST experiments, The Washington Post wrote this: "Cities and states could, of course, effect the same saving of daylight by simply keeping the clock on sun time and starting the day's work an hour earlier than customary." Farmers couldn't have agreed more. They already got up early and took advantage of daylight hours, so they didn't need an imposed, time-shifting system. They railed against the practice from the very beginning.

Unfortunately, those farmers fought an uphill battle, especially after 1975, when the U.S. Department of Transportation reported that DST saved energy. The study became the evidential foundation of the pro-DST movement, and little data emerged to refute the idea. Recently, however, some researchers have questioned whether the time shift is truly good for the power grid or for the health of citizens.

Arguably, the most compelling evidence comes from Matthew Kotchen, an economist at the University of California. When the entire state of Indiana began to observe DST in 2006, after spending many years on a half-and-half system, Kotchen seized the opportunity to conduct a before-and-after study of energy use. He and his team found that daylight saving time led to a 1 percent overall rise -- a rise! -- in residential electricity use, costing the state an extra $9 million [source: Kotchen].

Even more troubling, some scientists wonder if DST deleteriously affects human health. A German chronobiologist -- someone who studies natural physiological rhythms and other cyclical phenomena -- has shown that our circadian body clocks never adjust to daylight saving time. According to his research, moving clocks forward and back again interrupts normal sleep cycles, causing a sort of perpetual jet lag that leads to decreased productivity and quality of life and increased fatigue and susceptibility to illness.

That's not the worst of it. Swedish researchers examined heart attack rates in Sweden since 1987 and found that the number of heart attacks rose about 5 percent during the first week of daylight saving time. They published their results in the Oct. 30, 2008, issue of The New England Journal of Medicine, saying that disrupted sleep patterns may be linked to the cardiac episodes.

Perhaps Shakespeare was right after all. In King Henry VI, Part 1, he says, "Defer no time, delays have dangerous ends." Even though the famous playwright recorded these words some 193 years before Ben Franklin first conceived of daylight saving time while stationed in France, it could be sage and, ahem, timeless advice.