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Time change across Canada knocks circadian rhythm out of whack

Don鈥檛 forget to change your clocks this weekend!
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People walk by the steam clock in Gastown in downtown Vancouver, B.C., Tuesday, Dec. 31, 2019. THE CANADIAN PRESS/Jonathan Hayward

Time change discourse happens on a predictable cycle. Every year, twice a year, a chorus of Canadians decries the policy of springing forward and falling back.

It really is like clockwork.

Their calls to abolish daylight time have largely been fruitless, but experts say the semi-annual hubbub provides an opportunity to reflect on an even more important cycle: the circadian rhythm.

Most Canadians are set to turn their clocks back an hour on the morning of Nov. 3. Then, they will set them forward again on March 9, knocking their circadian rhythm out of whack.

Patricia Lakin-Thomas, a professor at York University and board member for the Canadian Society for Chronobiology, has long been interested in biological cycles.

鈥淲hen I go to a chronobiology conference, I鈥檓 hearing talks about everything from human societies to bacteria in a dish,鈥 she said. 鈥淲e鈥檙e interested in the general question of: how do living things tell time?鈥

The answer is the circadian rhythm, or what Lakin-Thomas describes as the 鈥渂rain clock.鈥

鈥淲e have rhythms in our guts and our liver and lungs and muscles, and the 鈥榖rain clock鈥 sends information to keep all of those in synchrony,鈥 Lakin-Thomas said. 鈥淭he 鈥榖rain clock鈥 has to get reset every day because it鈥檚 not very accurate, and it needs sunlight to do that.鈥

She calls the daily cycle of light and dark the 鈥渟un clock.鈥

Those two clocks are only tangentially related to the 鈥渟ocial clock鈥 鈥 the one hanging on your wall or displayed on your cellphone.

If Lakin-Thomas could rearrange society, she said she鈥檇 align the social clock with the sun clock.

鈥淭he fantasy, of course, is to go back to the way people did it before we had clocks. Go back to what farmers do and get up with the sun, that would be the ideal,鈥 she said.

鈥淏ut that would mean that your neighbours slightly to the west of you are getting up a few minutes later than you are, and your neighbours slightly to the east are getting up a few minutes earlier than you are, and in our industrialized society, we wouldn鈥檛 be able to make that work.鈥

Given the strictures of our post-industrial world, it鈥檚 worth understanding what we can do to help our brain clock align with the social clock, said Ralph Mistlberger, a psychology professor at Simon Fraser University who researches sleep.

鈥淲e鈥檙e interested in specific brain mechanisms, but we鈥檙e also interested in how the circadian system is organized, what kinds of components there are, how it鈥檚 controlled by external stimuli,鈥 he said of his research lab.

Mistlberger has been studying sleep for more than four decades, and in that time has also been contracted by various sports teams to offer insight on how to mitigate the effects of jet lag.

He suggests using light as a tool to help adjust their circadian rhythm.

There are certain photoreceptors in the retina 鈥 called melanopsinergic, intrinsically photoreceptive retinal ganglion cells 鈥 that are crucial for resetting the circadian rhythm.

These aren鈥檛 the rods and cones that give us our vision, they鈥檙e cells whose job is to detect the presence of light. Because of that, some blind people鈥檚 circadian rhythm is still affected by light, though others lack the photoreceptors.

For those who do have those photoreceptors, sighted or otherwise, the light has to be pretty intense, Mistlberger said, demonstrating with a studio light typically used in photoshoots and filming. It should be very bright and blue-toned, and you have to be pretty close to it.

鈥淚f I鈥檓 six inches away, if I hold this thing right up to my face, I can get a pretty good blast,鈥 he said. 鈥淭hat would be sufficient鈥hese things do work.鈥

You also have to use them at certain times of day, he said.

Light exposure only affects the circadian rhythm when the brain perceives it to be the morning and night, Mistlberger said, so getting sun in the afternoon won鈥檛 help wake you up.

That鈥檚 why many scientists are so opposed to clocks springing forward, he noted. It makes the sunrise happen later in the day 鈥 creating further distance between the 鈥渟un clock鈥 and the 鈥渟ocial clock鈥 鈥 which confuses the 鈥渂rain clock,鈥 because people don鈥檛 get the early-morning dose of sunlight they need to reset their circadian rhythm.

鈥淚t鈥檚 going to be harder to maintain an 鈥榚arly to bed, early to wake,鈥 schedule,鈥 Mistlberger said.

Though many scientists and doctors suggest we should stick with standard time 鈥 winter time 鈥 policymakers are mostly moving in the opposite direction.

In 2020, Yukon opted to observe daylight time year-round. That means that in the capital of Whitehorse, come winter solstice Dec. 21, the sun doesn鈥檛 rise until 11 a.m.

That same year, Ontario passed legislation to permanently remain on daylight time, but the bill was contingent on Quebec and New York state also making the move.

The case for daylight time is mostly related to business: if the sun is out later in the evening, people will stay out later and spend money.

This year, Quebec politicians joined the discourse. Late last month, Justice Minister Simon Jolin-Barrette launched a public consultation on the time change, and said the government may table legislation to abolish the tradition.

In addition to the Yukon, Saskatchewan doesn鈥檛 change its clocks, and neither does a small region of eastern Quebec, which remains on Atlantic standard time year-round.





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