Clocks falling back this weekend in much of the country will mean more rest and, ideally, less hurry Monday morning.
For chronobiologists, researchers who study our circadian rhythms, the end of daylight time and return to standard time in the fall holds a deeper health impact: it better co-ordinates our work and school schedules with what our bodies want to do, which is to follow the sun. Synchronizing our schedules this way is better for our long-term well-being, these experts say.
Even with that extra sleep we’re all looking forward to, spring forward and fall back remain divisive: some people want the early morning light that standard time brings, others the after-work sunshine of daylight time. No one likes change.
Medical experts have long warned about the health harms of seasonal time swings, with established links to sleep disruption, car and workplace accidents, strokes and heart attacks, particularly in the spring. Then there is the “social jetlag”: fatigue and hits to productivity at work.
In recent years, more jurisdictions in North America have been fiddling with the clock in another way, moving to year-round daylight time. Yukon chose this option and stopped seasonal time changes in the fall of 2020. British Columbia and Ontario passed legislation to switch to permanent daylight time, although neither province has moved ahead with the change, waiting for their American neighbours to follow suit. Both Britain and Russia tried out but ultimately abandoned the experiment of permanent daylight time, with Britain moving to seasonal time changes and Russia to year-round standard time.
While many Canadians resent the twice-annual time changes, researchers caution that locking the clock year-round on daylight time comes at a cost: even more of our morning hours would be shrouded in darkness through the long winters.
“I dropped my kid off at the bus and the sun wasn’t even up,” said Michael Antle, a University of Calgary psychology professor who studies circadian rhythms. “It was really dark. If we were to stick with this daylight time, it would be intolerable as we move through November into December.”
Chronobiologists say later dawns have profound impact on circadian rhythms that help regulate our hormones, temperature and nudge us to eat and sleep. These rhythms follow the rising and setting of the sun. Moving to year-round daylight time would throw these rhythms further out of whack with the “social clock” of our daily obligations.
“When our social schedule tells us to get up before the sun, we’re not very alert. We’re less productive and procrastinate more at work. We’re more likely to have accidents. Our reaction times are slowed,” Dr. Antle said.
Revealing 2019 research looked at people along U.S. time zone boundaries – living geographically side by side but an hour apart. Health records revealed those who had to rise an hour earlier than their neighbours had increased rates of chronic diseases linked to sleep deprivation and stress. The early risers were more likely to be overweight, obese, develop diabetes and certain types of cancer.
“You’re getting up an hour earlier before your body’s stress hormones are ready, before your insulin levels are ready for breakfast. You’re putting metabolic and physiological stress on your body,” said Patricia Lakin-Thomas, a biology professor who leads the Clocklab at Toronto’s York University, studying biological clocks.
Yukon has been on permanent daylight time for four years, after neighbouring British Columbia began planning a similar move in 2019. The territory’s online survey yielded some 4,800 responses, with people wanting to do away with time changes and opting for year-round daylight time instead. In Yukon, the change means exceptionally late sunrises in winter; by January, the sun won’t peek out until after 11 a.m. The tradeoff is more daylight later in the afternoons.
“The key thing in the North is that there are times of the year where we don’t get a lot of sunlight, and we can’t change that: We can’t get more or less by changing the clock. But what we can do is strategically place that daylight in a time of day that is most useful to folks,” said Andrew Smith, a Yukon intergovernmental relations officer who led the time change project.
He’s heard from Yukoners happy they can squeeze in a run or ski in the afternoon daylight. But he’s also fielded concerns from a seniors’ organization about elders rising early and facing darkness for hours. Still, based on Yukoners’ feedback, he felt the priority was eliminating seasonal time changes – “the annoyance of having to change the clocks, routines, bedtimes, commute times.”
From a health standpoint, chronobiologists are pushing for permanent standard time, arguing it brings us more in line with the sun’s daily progress. In 2022, Mexico abolished seasonal time changes, switching to year-round standard time.
But even that isn’t a perfect solution.
“The ideal for biology is we all do what people did in a pre-electric era, or what people around the world do today when they don’t have access to electricity. They get up with the sun, stay up until after dark when they’re tired and go to sleep,” Dr. Lakin-Thomas said. “But we don’t live in those societies and have to regulate time. There’s no perfect way to do this because days get longer in the summer, shorter in the winter. We’re never exactly in step with the sun.”
