Daylight Saving Time Bad for Health, Experts Claim

MONDAY, Nov. 4, 2019 (HealthDay News) -- Clocks were set back one hour on Sunday, but some health experts say it might be better if time changes ended for good.

It's more than an inconvenience, it's a potential health threat, they warn.

Over time, daylight saving time (DST) eliminates bright morning light that's crucial to synchronizing your biologic clock, possibly putting people at increased risk of heart attack, stroke and other harmful effects of sleep deprivation, said Dr. Beth Ann Malow, director of the Sleep Disorders Division at Vanderbilt University Medical Center in Nashville, Tenn.

During DST changes, adults lose an average of 15 to 20 minutes of sleep. Along with potential health problems, this may also increase the risk of serious or fatal accidents.

"People think the one-hour transition is no big deal, that they can get over this in a day, but what they don't realize is their biological clock is out of sync," Malow said in a Vanderbilt news release.

"It's not one hour twice a year. It's a misalignment of our biologic clocks for eight months of the year," she said. "When we talk about DST and the relationship to light we are talking about profound impacts on the biological clock, which is a structure rooted in the brain. It impacts brain functions such as energy levels and alertness."

In a commentary published Nov. 4 in the journal JAMA Neurology, Malow and her colleagues summarized large epidemiological studies that support a halt to setting clocks forward or back.

Some people have more flexible circadian rhythms and adjust quickly while others are more affected by the switch to and from DST, including children and people with neurological conditions, Malow said.

There's evidence that even slight time disruptions, like living on different sides of time zones, can be enough to affect a person's circadian rhythms, according to Malow.

While many sleep experts believe that doing away with time changes is a good idea, the U.S. federal government isn't considering any such move. However, many states are taking action. Since 2015, several states have passed DST exemption laws.

More information

The U.S. Centers for Disease Control and Prevention has more on sleep.