Congress is close to ending the twice-a-year clock change. That part is popular. But the version moving through Congress locks in permanent daylight saving time, not permanent standard time. Sleep medicine has been warning against this exact outcome for years.
Here’s the problem in one sentence: daylight saving time pushes clock time an hour ahead of the sun, and making that permanent means your body clock stays out of sync with daylight all year, every year.
What your body clock actually needs
Your circadian rhythm runs on light, not on a clock. Morning sunlight hits your eyes and tells your brain to stop making melatonin, raise cortisol, and start the day. This is called light entrainment, and it’s the single strongest cue your internal clock has.
Standard time keeps sunrise closer to the time most people wake up. Permanent daylight saving time pushes sunrise later, in some regions past 8 or 9 a.m. in winter. That means millions of people would wake up, commute, and start work or school while it’s still dark. Your circadian system doesn’t get the signal it needs until well into the morning, and that delay doesn’t just cost you alertness. It shifts your entire clock later, which makes it harder to fall asleep at a normal hour that night.
What the science says
The American Academy of Sleep Medicine has a formal position on this, and it’s the opposite of what Congress is passing. The AASM position statement states that the United States should eliminate seasonal time changes in favor of permanent standard time, which aligns best with human circadian biology, and that evidence supports the distinct benefits of standard time for health and safety, while also underscoring the potential harms that result from seasonal time changes.
This isn’t a fringe opinion. The statement was endorsed by 20 medical, scientific, and civic organizations, including the Sleep Research Society and the Society for Research on Biological Rhythms. The American Medical Association has also called for permanent standard time, warning that permanent daylight saving time overlooks health risks that permanent standard time would avoid.
A 2025 AASM survey found the public leans the same direction once you ask them plainly: 48% prefer standard time year-round, while only 24% favor permanent daylight saving time. Most people don’t realize the bill moving through Congress is the option sleep experts and much of the public don’t actually want.
We already ran this experiment, and it failed fast
This isn’t theoretical. The US tried permanent daylight saving time in 1974, during the oil crisis, as an energy-saving measure. It lasted less than a year.
Support started high and collapsed once winter mornings arrived. Approval was at 79 percent in December 1973 and had dropped to 42 percent by February 1974. The reason was simple: kids were walking to school in the dark. In the weeks after the change, eight Florida kids were killed in traffic accidents, and parents across the country reported sending their children to bus stops with flashlights because it was still pitch black outside.
By October 1974, President Ford signed legislation reversing permanent daylight saving time, ending the experiment early. And the energy savings that justified it in the first place never really showed up either.
The specific health and safety risks
Darker mornings mean more accidents. Most car crashes and pedestrian injuries cluster around the morning and evening commute. Push sunrise later and you push the riskiest driving hours into the dark, right when kids are walking to school and adults are the least alert.
Chronic circadian misalignment. A one-time clock change causes short-term problems like the “spring forward” spike in heart attacks and car accidents. Permanent DST is different: it’s not a one-time shift, it’s a permanent daily mismatch between your body clock and the sun. That’s linked to worse sleep quality, mood problems, and metabolic issues over time.
Teenagers are hit hardest. Teens already have a naturally later circadian rhythm. Add later sunrises on top of early school start times and you get teenagers trying to function on even less morning light exposure, which makes it harder for their body clocks to wake up on schedule.
It’s not evenly felt across the country. The farther west you live in your time zone, and the farther north, the worse permanent DST gets. Places like Michigan, western Texas, or the Idaho panhandle would see winter sunrises creeping toward 9 a.m.
The honest counterargument
To be fair, the case for permanent DST isn’t nothing. People genuinely like longer evening daylight for exercise, errands, and time with family after work. There’s also a real argument that evening light supports more economic activity in winter, more shopping, more time outdoors, which is part of why retail and tourism-heavy states have pushed hardest for this version of the bill.
The disagreement isn’t about whether daylight matters. It’s about which end of the day should get it. Sleep medicine argues morning light matters more for your health because it’s what keeps your circadian clock properly set. Everything else, mood, alertness, sleep timing, follows from that.
The bottom line
Ending the clock change is a good idea. Locking in daylight saving time as the permanent choice is not. If you want one thing to remember from this: your body doesn’t run on the version of time that gets you the most convenient evening. It runs on light, and morning light is the input it needs most. Permanent standard time gives you that. Permanent daylight saving time takes it away, permanently.
References
- Rishi MA, Cheng JY, Strang AR, et al. Permanent standard time is the optimal choice for health and safety: an American Academy of Sleep Medicine position statement. J Clin Sleep Med. 2024;20(1):121-125.
- American Medical Association. Sleep doctors’ orders: Use standard time 365 days a year. ama-assn.org.
- AASM Sleep Education. Daylight Saving Time. sleepeducation.org/resources/daylight-saving-time.
- Smithsonian Magazine. What Happened the Last Time the U.S. Tried to Make Daylight Saving Time Permanent
- Washingtonian. The US Tried Permanent Daylight Saving Time in the ’70s. People Hated It.