My pet dog serves as my natural alarm clock. His circadian rhythm is so in sync with his day-to-day routine that, weekday or weekend, he wakes my husband and me up at 7 AM. If his morning walk doesn’t follow soon thereafter or his lunchtime walk does not start by 12 noon, he runs between the door and me until I let him out.

So I am not really sure how to explain to him on November 1 that I am pushing our clocks back one hour to accommodate the yearly end of the strange ritual we North American humans follow known as Daylight Saving Time. I can already predict his reaction. He is going to paw at me at 6 AM (what was 7 AM for the preceding 8 months) until I get up. And, in this case, I think the Tibetan terrier mix has got it right.

Daylight Saving Time interferes with our circadian rhythms and our sleep, causing a slew of unintended consequences. At this point, the time change risks outweigh any perceived rewards. In the spring (the more difficult “spring forward” change), studies have linked the change to heart attacks,1 decreased work productivity,2 and the further sleep deprivation of our already sleep-deprived adolescents.3 The “fall back” change does fare better, but it has been linked with increased traffic accidents. According to, the increase of traffic accidents when Daylight Saving Time ends is likely due to the sudden shift to less driving visibility in the evening hours.4

From a purely sleep perspective, perhaps more telling is that the “fall back” adjustment only yields on average an extra 27 minutes of sleep. This is according to consumer sleep tracker manufacturer Withings, which in 2014 released data that “although we gain an extra hour, only 27 minutes are spent as extra time asleep. The remaining 35 minutes are added as time to enjoy a longer day.”5  


Sree Roy

Did you know that savvy researchers won’t let their lab rats observe Daylight Saving Time? In an NPR article published in November 2014, Lance Kriegsfeld explained, “In the midst of an experiment, simply changing the light-dark cycle by one hour can have such a pronounced impact on the physiology and behavior of the animals that experimental results gathered at this time may be inaccurate. My suggestion for anyone studying rodents is to either maintain a static light-dark cycle or avoid collecting any data until a few days after the time change—the latter solution also being relevant for researchers studying human populations.”6

We humans may be smarter than other animals in many key ways, but with regard to Daylight Saving Time, we should take an important lesson from the many species that do not arbitrarily disrupt their sleep patterns twice a year. The time has come to either present new evidence for Daylight Saving Time’s necessity or to end it for good.

Sree Roy is editor of Sleep Review.

1. Jiddou MR, Pica M, Boura J, Qu L, Franklin BA. Incidence of myocardial infarction with shifts to and from daylight savings time. Am J Cardiol. 2013 Mar 1;111(5):631-5.
2. Wagner DT, Barnes CM, Lim VK, Ferris DL. Lost sleep and cyberloafing: Evidence from the laboratory and a daylight saving time quasi-experiment. J Appl Psychol. 2012 Sep;97(5):1068-76.
3. Medina D, Ebben M, Milrad S, Atkinson B, Krieger AC. Adverse effects of daylight saving time on adolescents’ sleep and vigilance. J Clin Sleep Med. 2015 Aug 15;11(8):879-84.
4. Worland J. How Daylight Saving Time Can Be Dangerous. Oct 31, 2014.
5. Daylight Saving Time Only Yields 27 Minutes of Extra Sleep. Dec 3, 2014.
6. Lombrozo T. Why Lab Rats Don’t Observe Daylight Saving Time. Nov 3, 2014.