Daylight savings time (DST) heralds longer days, more sun, and warmer temperatures, but did you know that it is also associated with an increased risk of fatal car accidents? Multiple research studies have found a higher rate of car accidents on the Monday following the shift to Daylight Savings Time. The same association is not found with the Autumn time shift. But what’s behind the statistics? To fully grasp the problem and how we can manage it, we need an understanding of our internal body clocks.
Circadian Rhythms
Our bodies are naturally programmed to have daily cycles, called circadian rhythms, that govern many mental and physiological domains. For the sake of this discussion, let’s say that you typically have the common sleep schedule of an 11 p.m. – 12 midnight bedtime and a 6-8 a.m. rise time. The graphic below represents how your alertness would fluctuate throughout the day on such a schedule:
As you can see, there are separate alertness peaks mid-morning and in the late evening. Most people who keep the above sleep schedule will be maximally alert somewhere around 9 p.m.
Shifting Rhythms
It makes sense that our circadian rhythms are not fixed; otherwise, we’d never be able to adapt to new locations in different time zones. But circadian rhythms change relatively slowly and, for unclear reasons, it’s easier to “phase delay” our rhythms (be able to stay up later) than “phase advance” (be able to go to bed earlier); in general, it takes us 50% longer to adjust to phase advances than delays. The rule of thumb is that it we can phase advance approximately one hour per day.
What You Can Do To Adapt to Daylight Savings Time:
To ensure a smooth transition through Daylight Savings Time, the following countermeasures may be helpful:
- Try to pre-adapt before DST: Try going to bed 20 minutes earlier than usual for the three nights leading up to DST. Getting exposure to bright light first thing in the morning immediately after awakening for 15-20 minutes will help promote the phase advance of your circadian rhythms.
- Strategic use of melatonin: Melatonin exerts a powerful influence on our circadian rhythms. Taking some melatonin four to five hours before your desired bedtime can help you fall asleep at that time. So for instance, if your normal bedtime is 11 p.m., take melatonin at 6 or 7 p.m. on the Sunday of Daylight Savings Time. Research shows that a small dose of melatonin, like 0.5 mg or less, may be as effective as larger doses (3 mg is the most common dose) and is less likely to result in drowsiness.
- Strategic use of caffeine: If you’re dragging on Monday, March 13th, taking some caffeine can help combat mental fatigue. Just remember that it takes 20-30 minutes for your body to absorb the caffeine from your GI tract.
- Move to Arizona! The Grand Canyon State is the only state in the Continental United States that does recognize daylight savings time.
Author: Joseph Krainin, M.D., FAASM is on the Editorial Advisory Board of the American Sleep Association and the founder of Singular Sleep, LLC. He is a graduate of the Michael S. Aldrich Sleep Disorders Center at University of Michigan. Dr. Krainin is a fellow of the American Academy of Sleep Medicine and board certified in both Sleep Medicine and Neurology.
The primary mission of American Sleep Association (ASA) is to improve public health by increasing awareness about the importance of sleep and the dangers of sleep disorders. ASA was founded in 2002 by sleep professionals as a member-driven public awareness effort. The article was originally posted at The Dangers of Daylights Savings Time.