Fall back from daylight savings time may be good for the heart

Lloyd Resnick

Former Editor, Harvard Heart Letter

For most Americans, the clock giveth an extra hour this Sunday morning (November 6) at 2 am.

This “fall back” from daylight savings time can be discombobulating, but our hearts like it better than springing ahead. Three years ago, Swedish researchers reported in the New England Journal of Medicine that the rate of heart attacks fell on the Monday after the end of daylight savings time in the fall but spiked during the three weekdays following its start in the spring.

Sleep is the presumed link between these twice-a-year heart attack trends. The hour of sleep gained or lost is layered on what many sleep experts consider a baseline of sleep deprivation.  A century ago, the average American slept 9 to 10 hours a night. Now, a third of us operate on 6 hours or fewer. Insufficient sleep wreaks havoc with the body’s hormones and increases the levels of inflammatory chemicals that contribute to heart disease. Not enough sleep also keeps the fight-or-flight circuits of the nervous system on high alert.

There’s also a connection between these biannual clock adjustments and car crashes, although two studies came up with different findings. A Canadian study in 1996 found that the number of traffic accidents increased immediately after the spring time change and decreased after the fall adjustment. A similar study using U.S. data found an increase in accidents on both the Monday after the spring time change and on the Sunday after the fall one. Perhaps Americans are more likely than Canadians to use their extra hour at the end of daylight savings time for partying and wee-hour driving.

For the sake of your heart and overall safety, use the bonus hour you get this weekend for sleep. Experts recommend the following strategies to help ease the mind-body effects of the time change:

  • Go to bed on Saturday and get up on Sunday at your usual times.
  • Draw your bedroom blinds, because sunrise Sunday will arrive an hour early.
  • Expose yourself to daylight as soon as you wake up on Sunday.
  • Stick to the rest of your normal Sunday schedule, including mealtimes.

Related Information: Harvard Heart Letter


  1. Anonymous

    Excellent post!

  2. Heather Smith

    This is an interesting blog, we must all have the right time all the time. Thanks for posting this.

  3. Bob

    What a wonderful article, I learned a lot. Can’t wait until your next post. I look forward to more soon!
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  4. Louise

    Hi! When you have young kids Day Light Savings Time is a little tougher to appreciate…
    I am so sleepy as I am writing this!
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  5. Christin

    very intesting. thanks for sharing

  6. Douglas

    It’s correctly called Daylight Saving Time, not “savings.”

    As Casey Stengel would say, you could look it up.

  7. Jon

    My favorite thing about “falling back” is that it means a longer weekend! Good to hear that it may be better for the heart too though. 🙂
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