What Daylight Savings Tells Us About Sleep

Shifting from standard time to daylight savings time (specifically in the spring) is associated with increased risk of heart attack, cardiovascular-related death, stroke, acute atrial fibrillation, and overall 3% increased risk of all-cause death for an entire week following the change.

The research in this area has grown exponentially in the last decade. Movements have already begun in some countries and even states inside the US in terms of creating legislature to abolish daylight savings time. Why? Because we are finding that not only is daylight savings time proving to be a health threat, but a public safety threat as well.

It is interesting to first consider the origins of daylight savings. The original purpose of the concept of "saving daylight" was to better utilize natural light during the working day in order to preserve the use of artificial light (and therefore power/energy) for use in World War I. This was the beginning of modern daylight savings as we know it today, however there is also evidence of ancient civilizations implementing daylight savings in one form or another.

Either way, the idea of daylight savings is somewhat dated as it stands now in 2021 where more people are working not only into the evening, but even through the night (3rd shift, etc.) and consistently utilizing artificial light to do so.

The likely health factor in play here is the increase in sleep deprivation. Despite the time change, people still have to maintain their same schedules which often results in simply losing an hour (or more) of sleep. We see negative changes for the entire week after the time transition as well due to less natural light in the morning to help us wake up and more light in the evening impairing our ability to get to sleep. Furthermore, we don't see these negative consequences with the fall time change (think "gaining" an hour) or for the 2nd week following the spring change (the body begins to adapt to the new time).

Like any issue, there are pros and cons and I'm not in a position to make such decisions. The formation of daylight savings time was a political one, and would require the same process to be abolished. I would, however, like to highlight the health consequences following the time transition for your knowledge:

  • Increased hospital admissions

  • 3% increase in daily mortality

  • Increased risk of heart attack, stroke, and atrial fibrillation

  • Increased production of inflammatory markers

  • Increased heart rate and blood pressure

  • Increase in ~ 3% ER visits and 10% return visits

  • Increased in number of car accidents


Rishi MA, Ahmed O, Barrantes Perez JH, et al. Daylight saving time: an American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2020;16(10):1781–1784.

Roenneberg T, Wirz-Justice A, Skene DJ, et al. Why should we abolish daylight saving time? J Biol Rhythms. 2019;34(3):227–230.

Manfredini R, Fabbian F, De Giorgi A, et al. Daylight saving time and myocardial infarction: should we be worried? A review of the evidence. Eur Rev Med Pharmacol Sci. 2018;22(3):750–755.

Ferrazzi E, Romualdi C, Ocello M, etal. Changes in accident&emergency visits and return visits in relation to the enforcement of daylight saving time and photoperiod. J Biol Rhythms. 2018;33(5):555–564.

Poteser M, Moshammer H. Daylight Saving Time Transitions: Impact on Total Mortality. Int J Environ Res Public Health. 2020;17(5):1611. Published 2020 Mar 2. doi:10.3390/ijerph17051611

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