Sleep Experts Recommend Permanent Standard Time, Rather Than DST

Sleep experts tend to agree with U.S. lawmakers about getting rid of the twice-per-year time shift, with one exception: They typically call for standard time rather than daylight saving time.

After the Senate voted unanimously on Tuesday to make daylight saving time permanent, the American Academy of Sleep Medicine issued a statement that urged caution about adopting a fixed, year-round time with potential health risks.

“We do applaud stopping the switching during the course of the year and settling on a permanent time,” Jocelyn Cheng, MD, a member of the association’s public safety committee,told The Washington Post.

But “standard time, for so many scientific and circadian rationales and public health safety reasons, should really be what the permanent time is set to,” she said.

Now it’s up to the House of Representatives to decide what to do next. The legislation, which would take effect next year, must be passed by the House and signed by President Joe Biden before becoming a law.

Legislators and health experts have debated the shift in recent years. In 2020, the American Academy of Sleep Medicine released a position statement in the Journal of Clinical Sleep Medicine that recommended that the U.S. move to year-round standard time. Standard time is more aligned with humans’ circadian rhythms and natural light/dark cycles, the group wrote, and disrupting that rhythm has been linked to higher risks of heart disease, obesity, and depression.

At the same time, few studies have focused on the long-term effects of adopting daylight saving time. Most research has focused on the short-term risks of the seasonal shift, such as reduced sleep and increased car crashes, or circadian misalignment due to other things. Some health experts have called for more research before deciding on a permanent time, the newspaper reported.

Still, Tuesday’s statement from sleep experts received support from more than 20 groups, including the National Safety Council, National Parent Teacher Association, and the World Sleep Society.

“We have all enjoyed those summer evenings with seemingly endless dusks,” David Neubauer, MD, an associate professor of psychiatry and behavioral sciences at Johns Hopkins University, told the Post.

But daylight saving time “does not ‘save’ evening light at all, it simply steals it from the morning, when it is necessary to maintain our healthy biological rhythms,” he said.

Permanent daylight saving time would lead to more dark mornings, which opponents have said could be dangerous for kids going to school, adults driving to work, and overall sleep cycles.

“With daylight saving time, we are perpetually out of synchronization with our internal clocks, and we often achieve less nighttime sleep, both circumstances having negative health impacts,” Neubauer said. “Extra evening light suppresses the melatonin that should be preparing us for falling asleep. The later dawn during daylight saving time deprives our biological clocks of the critical light signal.”

The pros and cons of daylight saving time and standard time were debated during a hearing held by a House Energy and Commerce subcommittee last week. Sleep experts argued in favor of standard time, while other industry experts argued for daylight saving time to reduce crime, save energy, and help businesses that benefit from more daylight in the evenings.

“Everybody advocates a permanent time, but this difference between 1 hour back or 1 hour froward is not so clear in everybody’s mind,” Cheng said. “I would like to see further debate and some due diligence done on these health consequences and public safety measures before anything else goes forward.”


The Washington Post: “Sleep experts say Senate has it wrong: Standard time, not daylight saving, should be permanent.”

American Academy of Sleep Medicine: “AASM statement on Senate passage of permanent daylight saving time bill.”

Journal of Clinical Sleep Medicine: “Daylight saving time: an American Academy of Sleep Medicine position statement.”

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