Permanent standard time means keeping clocks on standard time year-round, eliminating the twice-yearly shift to and from daylight saving time (DST). Under this system, noon on the clock stays closely aligned with solar noon, the moment the sun reaches its highest point in the sky. It’s the option favored by sleep scientists and medical organizations because it matches the light-dark cycle your body’s internal clock depends on.
How Standard Time Aligns With the Sun
Standard time was originally designed so that the sun is roughly overhead at 12:00 p.m. in the center of each time zone. During daylight saving time, clocks jump forward an hour, pushing solar noon to around 1:00 p.m. That might sound like a minor shift, but it has a cascading effect: sunrises and sunsets both arrive an hour later by the clock, meaning darker mornings and lighter evenings.
Your circadian rhythm, the roughly 24-hour cycle that governs when you feel sleepy and when you feel alert, is set primarily by light exposure. Morning sunlight is the single most powerful cue for resetting that internal clock each day. When DST delays sunrise by an hour on the clock, your alarm still goes off at the same time, but your body is waking in darkness. Under permanent standard time, that morning light arrives earlier, keeping your biological clock in sync with your daily schedule.
Why Sleep Medicine Backs Standard Time
The American Academy of Sleep Medicine published a formal position statement calling for the United States to adopt permanent standard time, describing it as “the optimal choice for health and safety.” The statement, updated in 2023 with new supporting evidence, points to a specific problem: when the solar clock and the social clock fall out of sync, health suffers.
That desynchronization isn’t just about feeling groggy. The AASM links it to risks affecting both physical and mental health, as well as public safety. Evening light exposure delays the onset of your natural sleep window, making it harder to fall asleep, while your work or school schedule still demands the same wake-up time. The result is chronic, low-grade sleep loss. Circadian rhythms remain essentially locked to solar time regardless of what the clock says, so the negative effects of DST on sleep persist well beyond the few transitional days most people notice.
The Legal Situation in the U.S.
Under the Uniform Time Act of 1966, individual states can exempt themselves from daylight saving time by passing a state law. What they cannot do, without an act of Congress, is adopt permanent daylight saving time. This is an important distinction: the law gives states a one-way option. They can stay on standard time year-round, but they cannot stay on DST year-round.
Two states have already taken that option. Arizona stopped observing DST after 1967, largely because an extra hour of afternoon sunlight in the desert meant higher air-conditioning bills and no real benefit. Data showed that energy consumption actually increased when the state changed its clocks, the opposite of DST’s intended purpose. Hawaii opted out the same year. Sitting close to the equator, the islands get between 11 and 13.5 hours of daylight year-round, so shifting the clock makes little practical difference.
Meanwhile, there have been repeated attempts at the federal level to move the entire country to permanent daylight saving time instead. The Sunshine Protection Act was reintroduced in Congress in January 2025. It would make DST the permanent, year-round time. This puts it in direct conflict with the recommendation from sleep medicine experts, who argue that standard time is the healthier choice because of its alignment with morning light.
What the Traffic Safety Data Shows
One of the strongest practical arguments in the debate involves road safety, and the data is more complicated than either side often admits. The core tension is between darker mornings and lighter evenings.
A systematic review published in BMJ Open compiled studies from multiple countries. A U.S. study estimated that if DST were extended year-round, pedestrian fatalities could drop by about 13% overall thanks to lighter evenings. But it also projected that morning fatalities would increase by roughly one-third due to darker sunrises. A UK study spanning a decade found that the spring shift to DST reduced evening casualties by 11%, with no corresponding rise in morning casualties. An Irish study, however, found a 33.5% increase in morning casualties and a striking 105% increase in pedestrian casualties in the mornings after the spring clock change.
The pattern that emerges: lighter evenings generally reduce evening accidents, but darker mornings can create serious risks, particularly for pedestrians and children heading to school. Permanent standard time prioritizes brighter mornings, which is also the window when school commutes happen and when sleep-deprived drivers are most vulnerable.
Energy Savings Are Largely a Myth
The original justification for daylight saving time was energy conservation: more evening daylight means fewer lights turned on. But real-world evidence from a national experiment in Turkey, which adopted permanent DST in 2016, found negligible overall impact on electricity consumption. The savings simply shifted around the clock. Late-afternoon electricity use dropped by about 3.5% during winter months, but early-morning consumption rose by 3.4% as people turned on lights and heating in the dark. The two effects canceled each other out.
Worse, permanent DST increased the variance in electricity demand during winter, pushing peak usage into early morning hours. For power grids, higher peak demand is more expensive and harder to manage than steady, distributed consumption. Arizona’s experience told a similar story decades earlier: running air conditioners longer into hot summer evenings erased any lighting savings from the extended daylight.
Permanent Standard Time vs. Permanent DST
The public conversation often conflates two different proposals. Permanent standard time and permanent daylight saving time both eliminate the disruptive clock changes, but they set the clock an hour apart, and that hour matters.
- Permanent standard time keeps sunrise and sunset earlier by the clock. Mornings are brighter, which supports your circadian rhythm, improves alertness during morning commutes, and helps children get to school in daylight. The tradeoff is earlier sunsets, especially in winter.
- Permanent DST keeps sunrise and sunset later by the clock. Evenings stay lighter longer, which many people find more enjoyable for after-work activities. But winter mornings become significantly darker. In northern cities like Detroit or Seattle, sunrise wouldn’t happen until after 9:00 a.m. for weeks in December and January.
The medical consensus lands firmly on one side. The AASM’s position is that permanent standard time “aligns best with human circadian biology.” The concern with permanent DST is that it locks in the very misalignment between solar time and social time that causes health problems, not just for the transitional days, but permanently. Your body would spend every winter morning waking in deep darkness, fighting its own biology to get moving.
Polls often show public support for permanent DST because people imagine endless summer evenings. But the Russia experiment is instructive: the country switched to permanent DST in 2011, then reversed course to permanent standard time in 2014 after widespread complaints about dark winter mornings. The long summer evenings that people wanted came packaged with winter mornings that felt like the middle of the night.