Researchers Say Permanent Standard Time Beats Daylight Saving Time For Health

Canadian Analysis Finds Permanent Standard Time Fits the Body Clock Better Than Permanent Daylight Saving Time

In early January, the sun doesn’t rise until after 7:30 a.m. in cities from Vancouver to Halifax. Kids head to school under streetlights, and drivers scrape ice off windshields in the dark. A new analysis warns that permanent daylight saving time, the option several Canadian regions have already adopted, would push sunrise past 8:30 a.m., every winter, for good.

That’s the tradeoff at the heart of a new paper in the Canadian Medical Association Journal. Several Canadian regions are weighing which time to lock in once the twice-yearly clock change ends, and North American governments that have acted have largely picked permanent daylight saving time. A group of Canadian physicians and researchers reviewed the available evidence and reached the opposite conclusion: permanent standard time is the healthier choice.

Yukon switched to permanent daylight saving time in 2020. British Columbia followed in March 2026, and Alberta and the Northwest Territories did the same a month later. In July 2026, the U.S. House of Representatives passed a bill making daylight saving time permanent nationwide, and it now sits before the Senate. Major sleep and body-clock research societies have all called for permanent standard time instead.

Permanent Daylight Saving Time Delays the Morning Light the Body Clock Needs

Human bodies run on an internal clock slightly longer than 24 hours, so daylight has to reset it every day. Morning light nudges the clock earlier, which helps people wake on schedule, and evening light pushes it later. Many people spend much of the day indoors, away from bright morning light, while electric lighting and screens stretch exposure into the night. The result can be “social jet lag,” a mismatch between the body’s natural schedule and the schedule that work or school demands. Studies tie it to poor sleep and worse mental health.

Permanent daylight saving time worsens that pattern in winter by prolonging morning darkness. Permanent standard time keeps winter sunrises earlier, though it brings earlier sunsets and earlier summer dawns that may wake some people too early.

Evidence Favors Permanent Standard Time for Sleep, Mood, and School Performance

No volunteers took part, so there is no sample size. Four authors, spanning psychiatry, psychology, and economics, reviewed existing studies to compare the two options.

In U.S. county-level analyses, people on the western edge of a time zone, where the sun rises later by the clock, averaged as many as 2 additional suicide deaths per 100,000 people each year compared with those on the eastern edge, a gap that mimics the later sunrises permanent daylight saving time would bring. Limited evidence also links living farther west to higher rates of seasonal affective disorder, the clinical term for winter depression, which an estimated 1% to 3% of people in Canada live with.

A 2025 computer simulation found that both permanent options beat clock changes for health, but permanent daylight saving time’s benefits were a third lower than permanent standard time’s. One analysis of U.S. time zones found that an hour of later sunset cut weekly sleep by nearly an hour and long-term earnings by about 5%. In Florida, an extra hour of sunlight before school was linked to higher math and reading scores among teens. Later dusk has perks, but the paper says the downsides for sleep, productivity, and learning are better established.

Teens and Early-Shift Workers Face Greater Risk Under Permanent Daylight Saving Time

People with early shifts, early school start times, or caregiving duties, along with pedestrians, cyclists, and transit riders, could face more time in the dark, and the paper says those conditions fall more heavily on lower-income and minority groups. Teenagers are vulnerable as well. Puberty pushes sleep later while school start times stay early, a mismatch the paper says permanent daylight saving time would worsen, and one linked to sleepiness, low mood, and trouble functioning at school.

Three Countries Reversed Permanent Daylight Saving Time After Public Backlash

In 1974, the United States adopted permanent daylight saving time during the oil crisis, then abandoned it within a year after widespread opposition to dark winter mornings and limited evidence of meaningful energy savings. Russia adopted it in 2011 and reversed course in 2014 as dissatisfaction grew. Chile’s 2015 switch was also reversed after complaints about school attendance and scheduling disruption.

Japan, South Korea, and most of Mexico already use permanent standard time. Surveys in Mexico showed majority opposition to seasonal clock changes before their 2022 abolition, while opinion in Japan and South Korea was mixed.

Ending the twice-yearly clock change spares people a few weeks of sleep disruption each year. Locking in permanent daylight saving time could swap that for darker winter mornings, and the authors say the health effects of a permanent clock are likely to be chronic. Several Canadian regions have already made that choice, and based on the health evidence, permanent standard time is the better pick.

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Disclaimer: This article is for general informational purposes only and is not medical advice. It summarizes a published analysis and does not replace guidance from a qualified health professional. Anyone with concerns about sleep or mental health should speak with a doctor.

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