Four western jurisdictions are preparing to keep daylight time year-round, but a new analysis by British Columbia researchers says the available health evidence favours permanent standard time. The review, published Monday in the Canadian Medical Association Journal, examined multiple studies and warns that darker winter mornings could affect health, the economy and students’ well-being.

The change means clocks will not turn back on Nov. 1, when most of Western Canada would normally return to standard time. Instead, residents will remain on daylight time through the winter, shifting sunrise later by an hour compared with the usual clock change.

Ralph Mistlberger, a psychology professor at Simon Fraser University who has studied sleep and circadian rhythms for more than 40 years, said keeping daylight time is a mistake. He said people may favour more evening sunlight, but starting winter days in darkness can conflict with the body’s internal timing.

“You’re actually waking up at an earlier circadian phase. Your clock may still be telling your brain and your body that this is the sleep period. It’s not time to wake up yet,” Mistlberger said. “The same is going to happen in the evening. It’s going to be telling you this is still the wake period, it’s not time to go to bed yet.”

The researchers say standard time better aligns with the body’s rhythm. Mistlberger said disrupted sleep schedules can cause what scientists call “social jet lag,” when a person’s daily life and social calendar do not match their biological clock. Short-term sleep loss can be recovered from with a long sleep, he said, but chronic problems may lead to health concerns.

Those potential concerns include higher rates of metabolic disorders such as obesity and diabetes, along with cardiovascular disease. Mistlberger said epidemiological studies involving large populations have also found increases in cancer and some mood disorders.

The analysis was prepared by experts in economics, mental health and sleep. British Columbia, Alberta, the Northwest Territories and Manitoba announced this year they would adopt permanent year-round daylight time. The British Columbia government said the policy would “improve people’s overall health, reduce disruptions for families, simplify scheduling and provide an extra hour of evening light during the winter months.”

The province said more than 223,000 people took part in an online survey in 2019, with 93 per cent preferring a move to year-round daylight time. Mistlberger and Patrick Baylis, a co-author of the analysis, said the survey did not offer permanent standard time as a choice.

“The survey gave two options, which were comparing a switching regime, which is what we have previously had, to permanent daylight time. But those are the only two options,” Baylis said. He is an associate professor at the Vancouver School of Economics at the University of British Columbia.

Baylis said a major concern is the effect of dark mornings on students travelling to school. A study of students near the time-zone boundary in Florida found that an extra hour of sunlight before school was associated with higher math and reading scores among adolescents. The analysis described the effect as “comparable in magnitude to meaningful class-size reductions and largest at puberty when circadian rhythms are most sensitive.”

“At minimum we should be thinking about monitoring for some of these negative effects on schooling outcomes, particularly among adolescents,” Baylis said in an interview. He said measures could include more flexible or later school start times, or helping schools supplement the lack of natural light in the morning.

Economic research on the effects of daylight timing is limited, Baylis said, though some studies suggest sunlight exposure can influence productivity. One study examining differences in sunset timing within U.S. time zones found that an hour of later sunset reduced long-term earnings by about five per cent.

The review also describes past attempts to keep daylight saving time year-round. Russia adopted the policy in 2011 and reversed it three years later. The study said public dissatisfaction rose quickly, particularly in northern regions where winter mornings remained dark for longer, with critics pointing to disrupted biological rhythms, risks during morning travel and effects on daily functioning.

Most of Chile’s decision to change in 2015 was also reversed, the analysis said, after complaints about reduced school attendance, scheduling disruption and agricultural effects. In 1974, the United States adopted permanent daylight saving as an energy-conservation measure, but abandoned it within a year. The analysis cited widespread opposition to dark winter mornings, concerns about children travelling to school before sunrise, workplace safety concerns and limited evidence of meaningful energy savings.

The researchers recommend that jurisdictions choosing permanent daylight time take steps to reduce possible health effects and evaluate the consequences of the change. Along with school adjustments, the analysis points to the need to monitor outcomes.

Mistlberger said public education about the potential impact is important. He uses an adjustable light that can provide different colour temperatures at different times of day, while noting that natural sunlight is preferable to a lamp.

“You want cool in the morning. You want warm in the evening or warm in the afternoon,” he said. “And so, it goes from being more bluish in the morning to more reddish in the evenings. Both of those are important because artificial light affects your clock.”

He advised people to get outdoor light early in the day, even when winter sunrise comes later than it would under standard time. “You want to get as much light exposure as you can as early as possible in the day when you go outside. So, even though the sunrise is going to be later than usual, it’s going to help you to get outside as soon as there is some sunrise.”

Based on reporting by Global News Edmonton.