Permanent daylight saving time means keeping clocks set one hour ahead of standard time all year long, eliminating the twice-yearly time change. Instead of “falling back” in November and “springing forward” in March, the clocks would stay in their summer position permanently. The practical result: more evening light year-round, but darker mornings, especially in winter.
How It Differs From Standard Time
To understand what permanent DST would look like, it helps to know what the two settings actually do. Standard time is the “baseline” clock setting for each time zone, aligned more closely with solar noon (when the sun is highest in the sky). Daylight saving time shifts that clock forward by one hour, moving a chunk of morning light into the evening.
During summer, the difference is barely noticeable because there’s plenty of light to go around. The real impact shows up in winter. Under permanent DST, a city like New York wouldn’t see sunrise until nearly 8:20 a.m. in late December, while sunset would push past 5:30 p.m. Under permanent standard time, that same day would have sunrise around 7:20 a.m. and sunset closer to 4:30 p.m. So the tradeoff is straightforward: permanent DST buys you brighter evenings at the cost of much darker mornings.
Why the U.S. Can’t Just Do It
Federal law currently blocks states from adopting permanent DST on their own. The Uniform Time Act of 1966 gives states the option to exempt themselves from daylight saving time entirely, staying on permanent standard time. Arizona and Hawaii already do this. But the law does not allow the reverse. States cannot choose to stay on DST year-round without an act of Congress.
That’s where the Sunshine Protection Act comes in. The bill, which has been reintroduced multiple times, would make daylight saving time permanent nationwide. The Senate unanimously passed a version in 2022, but it stalled in the House. The most recent version was introduced in January 2025 and has not advanced further. Until Congress acts, the twice-yearly clock change remains the default for most of the country.
The U.S. Already Tried This Once
The idea isn’t new. In response to the 1973 energy crisis, Congress enacted year-round DST starting in January 1974. The policy quickly became unpopular. Parents objected to children walking to school in pitch darkness during winter mornings, and the expected energy savings were minimal. Congress reversed course, and standard time returned for winter months by October 1974. The episode is a useful reminder that permanent DST polls well in the abstract (more evening light sounds great) but looks different when people experience months of dark mornings firsthand.
What It Would Mean for Sleep
Sleep scientists have a clear preference, and it’s not permanent DST. The American Academy of Sleep Medicine has formally recommended that the U.S. adopt permanent standard time instead, calling it the option that “aligns best with human circadian biology.”
The concern centers on morning light. Your body’s internal clock uses early sunlight as its primary reset signal each day. When mornings stay dark, that signal is delayed, making it harder to wake up and fall asleep at appropriate times. Research comparing populations living on the eastern and western edges of time zones (a natural experiment, since western-edge residents get evening light later and morning light later) found that an extra hour of natural evening light reduced sleep by an average of 19 minutes per night and increased the likelihood of reporting insufficient sleep. That may sound small, but 19 minutes of chronic sleep loss compounds over weeks and months.
Permanent DST would essentially push the entire country toward “western edge” conditions year-round, creating a persistent mismatch between clock time and the body’s biological rhythm. Sleep researchers call this social jet lag: your alarm clock says one thing, but your brain’s internal clock says another.
The Safety Tradeoff
One of the strongest arguments for permanent DST is road safety. More evening light means fewer pedestrians and cyclists hit by cars during the busy after-work hours. Data on the existing spring time change shows pedestrian and cyclist fatal crashes drop by 24% in the weeks after clocks move forward and evening light increases. The flip side: motor vehicle occupant fatal crashes rise by 12% in that same period, likely tied to the lost hour of sleep and darker mornings.
When clocks fall back in autumn, the pattern reverses. Vehicle occupant fatal crashes drop by about 7%, but pedestrian and cyclist deaths jump by 13% as evening darkness returns. Some researchers have found that crashes don’t increase or decrease overall but simply shift between morning and evening hours depending on when it’s dark. The net safety benefit of permanent DST is genuinely debated, not settled.
Who Supports Which Option
The debate has two distinct camps, and they’re often talking past each other. Polls consistently show that most Americans want to stop changing clocks. Where they split is on which time to keep.
People who favor permanent DST tend to focus on lifestyle benefits: longer evenings for outdoor recreation, less disruption to after-school activities, and the simple appeal of driving home from work while it’s still light. Industries tied to outdoor evening activity, like golf and retail, have historically supported extended DST for similar reasons.
People who favor permanent standard time tend to focus on health. Beyond the AASM, organizations including the American Medical Association and the Society for Research on Biological Rhythms have endorsed standard time as the healthier option. Their argument is biological: the body’s clock evolved around the solar cycle, and permanent standard time keeps clock time closer to that natural rhythm.
Both sides agree on one thing: the current system of switching twice a year is the worst option. The transitions themselves are associated with short-term spikes in heart attacks, strokes, and traffic accidents as millions of people adjust. The real question is which permanent setting the country would land on, and that decision involves weighing evening convenience against morning biology.