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Monday, October 21, 2013

Can Daylight Savings be Dangerous?

Our circadian rhythms are dictated by the light and dark cycles in our environment. Every one of our cells has an internal clock that responds to changes in daylight. Special proteins called cryptochromes in our skin cells are sensitive to light’s blue spectrum, so whenever we’re bathed in light, our bodies get the message to wake up.

Light and dark cycles influence levels of key hormones like cortisol and melatonin that help regulate bodily processes including inflammation and immunity, which help determine our resistance to disease.

When the light and dark cycles in our environment suddenly change, even by only an hour, this change can disrupt the way our bodies work. It also slows reaction time and has been linked to an increase in traffic accidents.

Researchers in Michigan analyzed a decade of national traffic statistics and found that during the week before the daylight savings time change, 65 fatal crashes were reported. The week after the time change, 227 were reported. The Insurance Institute for Highway Safety of Arlington, Virginia calculated that using daylight savings time year-round could save approximately 200 deaths each year.


Plainis S, Murray IJ, and Pallikaris IG. Road traffic casualties: understanding the night‐time death toll. Injury Prevention. 2006; 12(2): 125–128.

Sullivan JM and Flannagan MJ. The role of ambient light level in fatal crashes: inferences from daylight saving time transitions. Accident, Analysis and Prevention. 2002;34(4):487-98.

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