Daylight Saving Time’s Effect on Mental and Physical Health

Dog sleeping on top of humanIn the 1780s, when Benjamin Franklin unintentionally first proposed a version of what we now call Daylight Saving Time (DST), he likely never envisioned the complications it might manifest in modern life. At the time, the benefits to an agrarian culture were evident—including maximizing sunlight hours and reducing overall candle usage. Less understood was the impact such shifts could generate to circadian rhythms, stressing both mind and body.

The implications continue to stoke a decades-old global debate over the wisdom and value in such annual time shifts. DST has been regularly shown to increase heart attacks, car crashes, and workplace accidents—both in the spring as clocks roll ahead and in the fall as they adjust back to true time. Such changes may also impact rates of anxiety and even suicidality with each resetting of the clock.

Side Effects of Daylight Savings

The disruption of sleep from DST can often mirror the effects of jet lag. The loss of a single hour of sleep in the spring—or the further disruption of sleep and waking cycles in the fall—can be enough to trigger an emotional response, a lapse in judgment, or even a potential catastrophe.

DST has been suggested as a factor in several man-made disasters, from the Exxon Valdez oil spill to the accident at Chernobyl Nuclear Power Plant in Ukraine. On smaller scales, the accumulated accidents and oversights in which DST may have played a role is incalculable.

Two linked studies published in BMC Biology in 2007 concluded that circadian rhythms—which drive the human body clock—often never fully adjust to the time change in the spring, and instead can remain disrupted until clocks reset months later. The first study utilized surveys from more than 50,000 Europeans (where DST is implemented annually, known there simply as “Summer Time”) while the second study analyzed the sleep patterns of 50 subjects in the eight weeks surrounding each annual time shift.

The authors of a 2016 Finnish study found the overall rate of ischemic strokes—the most common type of stroke—is 8% higher in the two days following DST, while the likelihood for those with cancer of having a stroke increases to 25%. Seniors older than 65 were found to be 20% more likely to have a stroke, even though hospital deaths by stroke were not shown to rise in the week following DST.

For their findings, the researchers relied on 10 years of stroke data, in which they compared the rate of strokes among 3,033 hospital patients in the week following DST against a group of nearly 12,000 who were admitted at least two weeks before or after the time change.

In 2015, research from Tel Aviv University found sleep disruption can stir anxiety and increase the likelihood of emotional outbursts, while an Australian effort examining decades of death records concluded the time shift brought about a regular, if marginal, increase in suicides.

A Century of Debate

Following World War I, Congress had to secure enough votes to override President Woodrow Wilson’s veto of a bill that would abolish the practice of DST. Though states and localities could chose to implement their own versions of the time shift each year, no federal mandate existed again until World War II, with Franklin Roosevelt reinstating it year-round to improve production of goods needed for the global conflict.

DST did not come into official practice until the U.S. Uniform Time Act of 1966, with various extensions and modifications made in the years since. Today, the debate continues alongside greater scrutiny of the practice. Meanwhile, industry analysts, public safety officers, and psychologists have become more watchful around the shifts—better aware of the inherent side effects associated with simply changing a clock.


  1. American Academy of Neurology (2016, February 29). Does Daylight Saving Time Increase Risk of Stroke? Retrieved from
  2. Holmes, L. (2015, September 24). Science Says Your Lack Of Sleep Is Making You A Miserable Person. Retrieved from
  3. Kattermann, T. (2, November 20). The human circadian clock’s seasonal adjustment is disrupted by daylight saving time. Retrieved from
  4. Klein, C. (2012). 8 Things You May Not Know About Daylight Saving Time. Retrieved from
  5. Lopatto, E. (2016, March 12). Daylight Saving Time is hot garbage. Retrieved from
  6. Simon, E. B. (2015, April 6). The Journal of Neuroscience. Society for Neuroscience. Retrieved from
  7. Time and Date. (n.d.). The History of Daylight Saving Time. Retrieved from
  8. Varughese, J., & Allen, R. P. (2001). Fatal accidents following changes in daylight savings time: The American experience. Sleep Medicine, 2(1), 31-36.
  9. Yahoo! Health. (2015, March 9). Watch Yourself! Today Is One Of The Most Dangerous Days Of The Year. Retrieved from

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  • Leave a Comment
  • Baye

    March 17th, 2016 at 3:21 PM

    I don’t need a team of scientists to tel me how this time change messes up my life. A week in and I am still having trouble sleeping.

  • Colton

    March 18th, 2016 at 11:06 AM

    The general consensus seems to be that we all hate it
    so if it is really so detrimental
    then why not change the law and make it so that we don’t have to endure all the madness that it seems to cause?
    let’s just choose to live on real time, not some made up version of it.

  • tyler

    March 21st, 2016 at 7:50 AM

    So now we know that there can be real harm inflicted with these constant changes of the clock. One hour a few times a year seems so benign and yet the evidence is out here that it is anything but that. There are some real health concerns that people face as a result and I don’t believe that the hour gained or lost depending on the time of year is worth all of that bodily upheaval.

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