How Does Daylight Saving Time Affect Your Health?

alarm clock in bedroom
From the WebMD Archives

On March 11, most of us (unless you live in Arizona or Hawaii) will set our clocks ahead one hour. Losing an hour of sleep to gain an extra hour of sunlight may seem like a small change, but springing forward interrupts your circadian rhythm -- or your sleep-wake cycle. 

Your body has to adjust to the new time in the same way it would if you flew from Chicago in the Central time zone to New York City in the Eastern time zone, says David Prerau, PhD, author of Seize the Daylight: The Curious and Contentious Story of Daylight Saving Time

This shift can be stressful for your body and can affect your well-being in some surprising ways.

You’re Safer on the Roads (in the Long Run)

Although more accidents may occur the first week after the time change due to drowsy drivers, other studies confirm the net effect is positive. The extra evening light helps cut the number of car accidents over the 8 months of daylight saving time, Prerau says. 

You Can Fit in Exercise After Work

People are more likely to do something active outdoors (and watch less TV) since it’s lighter outside for longer. One study found that people burn about 10% more calories during daylight saving time.  

People With SAD May Benefit

The switch to daylight saving time may help people who have seasonal affective disorder, or SAD, Prerau says. SAD is a type of depression that corresponds with the changing of the seasons, and symptoms worsen with the lack of sunlight in the fall, while the longer hours of light in the spring and summer can help lower symptoms of depression, research suggests. 

You May Be Less Focused at Work

Employees may waste more time at work by “cyberloafing” (think: watching YouTube videos or reading celeb gossip sites) on the Monday after springing forward. A study linked this drop in productivity to lower quality and quantity of sleep the night before. 

Night Owls Will Feel Sleepier Than Early Birds

One study found that people who tended to go to sleep later reported feeling more tired during the day for 3 weeks after the time change, compared with people who went to bed earlier.

Heart Attacks Are More Likely to Happen, Then Level Off

Some research has found a rise in heart attacks the Monday after the time shift. Researchers link this to the change in the sleep-wake cycle and stress about the new workweek ahead. However, this higher risk drops off the Tuesday after the time change, so the overall heart attack incidence stays about the same. 

Preparing for Sleep Shifts

If you find your sleep-wake cycles tend to be disturbed by the time change, you can offset the consequences by tacking on 30 minutes of sleep the two nights before setting the clocks ahead or getting an extra hour of sleep the night before, Prerau suggests. 

WebMD Feature Reviewed by Arefa Cassoobhoy, MD, MPH on March 08, 2017

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