Permanent Daylight Saving Time: The Health Impact on Americans

Congress is once again pushing to lock the clocks in place for good, but the doctors who study sleep for a living say the version lawmakers keep picking could make Americans sicker, not healthier.

Story Snapshot

Nearly every major sleep and circadian science group opposes permanent daylight saving time and instead backs permanent standard time.
A 1973-74 experiment with permanent daylight saving time was scrapped within a year after dark winter mornings sparked public backlash.
Stanford researchers say permanent daylight saving time would only deliver about two-thirds of the health benefits of ending seasonal clock changes entirely.
Congress keeps reviving the Sunshine Protection Act despite years of warnings from sleep specialists.

Congress Revives a Familiar Fight Over the Clock

Senators Marco Rubio and Edward Markey reintroduced the Sunshine Protection Act, a bill that would end the twice-a-year clock switch by making daylight saving time permanent nationwide. The idea keeps resurfacing because voters like longer evening light. But the medical groups that study sleep and body clocks have lined up almost unanimously against this specific version of the fix.

More than 20 medical organizations, led by the American Academy of Sleep Medicine, formally endorsed permanent standard time instead of permanent daylight saving time. Their position statement argues standard time matches how the human body naturally tracks light and darkness, while daylight saving time pushes sunrise later, keeping people out of sync with their own internal clocks.

What Doctors Say Happens to the Body

Research already shows that just changing the clocks twice a year raises the short-term risk of heart attacks, strokes, and car crashes for days afterward. Sleep doctors argue that switching to permanent daylight saving time would not end that strain. It would instead lock in a permanent mismatch between the body’s internal clock and the sun, especially during dark winter mornings.

Stanford University researchers modeled county-by-county light exposure and health data across the country. They found permanent standard time would benefit the most people. Permanent daylight saving time would still help, delivering roughly two-thirds of the health gains compared with simply ending the seasonal clock switching altogether.

America Already Tried This Once

The United States tested permanent daylight saving time in 1973 and 1974 during an energy crisis, hoping to cut power use. The experiment failed fast. Dark winter mornings were blamed for a rise in deaths among children walking to school, and Congress repealed the law before it even finished its first full year.

Why the Popular Choice Keeps Winning Anyway

Sleep researchers say the disconnect comes down to politics, not science. “If you look at the expert consensus from the scientific societies that focus on sleep, health and circadian rhythms, all of them agree this is a bad idea,” one University of Colorado Boulder sleep scientist said, adding that ending the clock changes is right, but lawmakers are choosing the wrong fixed time.

Starting now, I will be choosing standard time. DST is imaginary time and is not healthy.

Permanent standard time is generally considered healthier than daylight saving time (DST), according to major sleep and medical organizations.

Why Standard Time Aligns Better with Health… pic.twitter.com/rVGWj5Zl9a

— DanceWithMe (@goforthdancing) July 19, 2026

Not every finding in this debate is settled. A group of physicists recently challenged the methodology behind a widely cited 2025 study on daylight saving and obesity risk, arguing its statistical approach could not support the conclusions drawn. That dispute is narrow, though, and does not change the broader agreement among sleep and circadian medicine groups that permanent standard time offers the safer path forward for public health.