4 Weird Ways the Time Change Affects Your Health


Soak up the extra morning light to stave off the winter blues. (Photo by Aleksander Nakic/E+/Getty Images)

When the phrase “turning back the clock” is applied to the antiaging benefits of a new skincare routine, there is very little downside. But the way literally turning back the clock — adjusting your schedule by just an hour every autumn — affects your body is less clear cut. The main question: Does the extra 60 minutes you scored this weekend give your health a boost — or hurt it? 

The majority of studies focus on the downsides of springing forward in March (and losing an hour of sleep), with effects ranging from an increase in “cyberloafing” (that is, surfing the Web when you should be working) to an uptick in suicides among men. “The autumn change is usually the more benign one,” said Michael Grandner, a instructor in psychiatry at the University of Pennsylvania and a member of the Center for Sleep and Circadian Neurobiology. “Most people’s internal rhythms aren’t exactly 24 hours — they’re closer to maybe 24.5 hours. So adding time to the day is really easy for the body to do.” 

But the fall transition — typically associated with one thing —more sleep! — still throws off your internal body clock, which means it can affect your health, said Dr. Alfred Lewy, director of the Sleep and Mood Disorders Laboratory at Oregon Health & Science University. Think about it: “We try to force our sleep-wake cycle into a new time, but our body rhythms are still stuck on the old time,” he said.

Related: Cheerful? Depressed? The Season in Which You Were Born May Hold the Key

Why can’t our bodies cope with a simple 60-minute shift? “You would think that a one-hour change would be easy to adjust to — it’s known that flying one hour east or west doesn’t produce jet lag,” Lewy told Yahoo Health. Problem is, with the autumn change, you’re trying to shift your body clock later, while morning sunlight is invading earlier. “The new sunlight-dark cycle is working against the direction of change we need to make,” he said. And that means the effects of daylight saving time — and the return to standard time in the fall — extend far beyond the time you see on your iPhone (or your electric bill).

1. Your risk of being in a car accident may increase

You know driving while drowsy is risky — but the midnight hour isn’t the only time the threat of an accident may loom large. The week after daylight saving time comes to an end — that’s now! — there’s a 7 percent increase in car crashes, a Texas A&M University study found. The uptick in morning traffic accidents is even greater: 14 percent. Why the surge in roadway chaos? “Just like when you have jet lag, your performance falls. Your cognitive abilities decrease,” explained Lewy. “Even though you’re not [necessarily] sleep deprived, your rhythms aren’t adjusted, and that produces deficits in performance.”

Driving home in the dark may be to blame for accidents in the evening. “It’s getting dark an hour earlier, but your social schedule isn’t changing,” Grandner told Yahoo Health. “That might make us a little more tired at the end of the day.” Plus, as the National Highway Traffic Safety Administration warns, it may take some time to adjust to low-light driving, when you’re used to commuting home in broad daylight. 

2. Your odds of a heart attack may drop

The season of holiday stress is officially upon us — but the fall time change may give your body a brief break from all the cardiac strain. In a 2014 study of 42,060 people, researchers found a 21 percent decrease in heart-attack cases on the Tuesday following the fall time change. By contrast, they noticed a 24 percent increase in heart-attack incidence on the Monday after the clock springs forward in March. 

The simplest explanation: The spring shift forward disrupts your sleep-wake cycle, leading to inflammation; this physiological strain may compound the inherent stress of Monday mornings, translating to an increased risk of a heart attack.

Conversely, if you gain an hour of sleep when the clock winds back — which not all of us do, by the way (see below) — your odds of a chest clutcher may decline, thanks to the decreased stress on your system, the scientists say. “Most people have heart attacks in the morning, because your blood pressure dips overnight and then rises sharply at the end of the night into the morning,” said Grandner. “Staying in bed a little longer might give your body more time to recover — to bring your blood pressure back up to daytime levels, without it being such a sharp increase.” 

3. Your mood may improve 

As the weather gets colder, our moods tend to get icier. Blame it on the dark mornings associated with the changing seasons: “You’re waking up before dawn,” said Lewy. “That seems to trigger winter depression in vulnerable people.” But in the weeks following the fall time change, your wake time may actually sync with the sunrise, giving your mood a boost — albeit temporarily. “Morning light is one of the most powerful things you can [expose yourself to] in order to stave off winter blues,” Grandner said. That means people with cold-weather depression are enjoying “a little bit of a respite right now,” Lewy said. “The time change kind of stops the process for a few weeks, because we go back to waking up into sunlight.” 

Related: Ways to Deal with the End of Daylight Savings Time

4. The quality of your sleep may take a hit

Think the autumn time change equals an extra hour of sleep? Maybe not. There’s little evidence that people take advantage of those 60 minutes of additional shuteye time — in fact, the sudden shift in your schedule may actually cause you to lose sleep the week after you turn back the clock, according to an article in Sleep Medicine Reviews.

“People may stay up later [after the time change] — that’s a little bit easier to do,” Lewy told Yahoo Health. “But they’re not sleeping in that hour later, because their body clock is waking them up. So they’re not actually getting that extra hour of sleep on Saturday night, and then on Sunday night, they actually be getting less sleep than they did the week before.” 

And the z’s you do get may not be as sound: After the fall transition, people tend to experience a decline in sleep efficiency — that is, the amount of time in bed spent actually snoozing, not just restlessly lying there, a Finnish study found. This was especially true among morning people.

If you find yourself struggling to adjust year after year, try this strategy the next time around: Starting on the Friday before the fall transition, take .3 milligrams of melatonin — you may have to cut up a tablet to get such a small dose — when you wake up; do this through the Monday after the time change. “Melatonin is a chemical dark signal. It shifts the body clock later and counteracts the effect of morning light,” explained Lewy. This tiny dose probably isn’t enough to make you drowsy — but it will help your body adjust more quickly to the change, he said.