What Daylight Saving Time Switch Does To Your Sleep Pattern

As the clocks "go forward" for large parts of the U.S. this weekend, you may well miss the resulting lost hour of sleep. However, the health impacts of the shift into daylight saving time (DST) are much larger. This is the argument of biologist professor Carla Finkelstein of Virginia Tech and her colleagues at the Society for Research in Biological Rhythms, who advocate for the elimination of DST in favor of permanent standard time. "Research shows the daylight saving time messes with our biological [circadian] clocks by reducing morning sunlight exposure, which pushes our sleep schedules later and can have negative impacts on our health," Finkelstein, who studies the impact of circadian disruptions on cancer, told Newsweek. "Staying on standard time year-round is much better for our circadian rhythms, overall health, and well-being," she said. The origins of DST lie in Europe, where it was first introduced in Germany in 1916 with the goal of saving on the fuel used to light lamps. After a patchy and inconsistent initial uptake beginning in 1918, the transportation industry successfully lobbied for uniform implementation in 1966. The extent of DST was increased from its original six month stretch over May through October first forward to the first Sunday in April in 1987, and then in 2007 to cover the period from the second Sunday in March to the first Sunday in November. At present, however, not everywhere in the U.S. follows DST—with exceptions including the states of Arizona and Hawaii and the territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico and the Virgin Islands. For Finkielstein, these exceptions merit expansion.

"We always need to be in constant harmony with the environment—and it is absolutely crucial to maintain your physiology and behavior in sync with any particular change that happens in the environment," Finkielstein said. "So you have a political decision of implementing this daylight saving time with this idea that this will save energy, which was never really proven," she added. "This one hour switch causes a mismatch between your internal clock and the sun...you will be kind of in a different time zone. This mismatch is very important and influences your health a lot." In the first couple of weeks after the clocks change, Finkielstein explains, we see an increase in various conditions—from arterial fibrillation and stroke through to deaths, suicide attempts, infant sudden deaths and visits to emergency rooms. "On top of that, because early in the morning is dark, there are more traffic accidents and they are more deadly," Finkelstein noted. Studies have also linked the clock change, she notes, to sleepy children underperforming in school—while the stock market tends to be more volatile immediately after the change. Comparisons between populations that practice DST and those that do now, however, have also hinted at longer term health issues, Finkielstein says, that results from repeating the clock changes every year. "There are chronic consequences—chronic meaning that there are long term consequences that arise from these changes," she explained.

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DST, she added, has been associated with a "10 percent increase in obesity, 19 percent increase of heart attack over the lifespan of an individual and 5 percent more type 2 diabetes." "From the cancer standpoint—because I cannot leave that aside—there is a 9 percent increase in men's cancer and a 12 percent increase in women's cancers," she explained. Put together, the practice of daylight saving time increases the U.S.'s health care bill by some £2.3 billion (around $2.96 billion) each year, according to Finkielstein. One might ask why scientists in favor of eliminating the clock changes would prefer to stay in standard time, rather than switch to DST permanently. As Finkielstein noted, an experiment to this effect was done in the 1970s, amid the crisis caused by the Organization of Arab Petroleum Exporting Countries' oil embargo, when—in an effort to save fuel—the U.S. congress enacted a trial switch to full DST. Despite broad public support at first—with increased daylight to enjoy in the evening—such dropped from 79 to 42 percent over the winter, driven in no small part by an increase in morning traffic accidents involving children en route to school. "Congress rolled back the measure by a vote that was 383 to 16, clearly demonstrating how bad the idea is," Finkielstein said. Just this week, Utah's representative Celeste Maloy introduced a bill to Congress that would allow states to choose whether or not to practice DST. While the outcome of that will remain to be seen, Finkielstein has some advice to people feeling the effect of the clock change: try not to go to sleep late and not to drive in the morning. "I think the take-home message that my society wants to pass to the public is that we should not fight our internal clock," Finkielstein said. "The more in sync you are with your environment, the healthier your life will be." Do you have a tip on a health story that Newsweek should be covering? Do you have a question about circadian rhythms? Let us know via science@newsweek.com.