The onset of daylight saving time can be hazardous to your health


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Dreading this Sunday’s change to daylight saving time, when we’ll all lose an hour of sleep? Fatigue isn’t the only thing you’ve got to worry about, according to scientists who have studied multiple aspects of the annual “spring forward” from 2 a.m. to 3 a.m.


  • The number of serious heart attacks jumps 6% to 10% on the first three workdays after the start of daylight saving time, according to a 2008 Swedish study published in the New England Journal of Medicine.
  • Men are more likely to commit suicide during the first few weeks of daylight saving time than they are during the rest of the year, according to a 2008 Australian study in the journal Sleep and Biological Rhythms.
  • The number of traffic accidents in the U.S. spikes on the Monday after the clocks move forward, researchers reported in the journal Sleep Medicine in 2001. Canadian researchers have pegged the increase there at 8%, according to a 1996 study in the New England Journal. In Sweden, it jumps by 11%, according to a 2000 study in the journal Accident Analysis & Prevention.
  • Economists have found that sleep-deprived traders typically produce “large negative returns on financial-market indices” in the week following the shift to daylight saving time, according to a 2000 paper in the American Economic Review.

Health concerns helped persuade officials in Kazakhstan to quit switching back and forth between standard time and daylight saving time in 2005, according to this report in Kazakhstan Today.


-- Karen Kaplan