This weekend, Quebecers will have to turn back their clocks one hour as daylight saving time ends at 2 a.m. Sunday, allowing people to catch up on some sleep.

However, the night will now fall earlier, which could have adverse effects on some people, such as feeling tired or having more difficulty falling asleep and waking up.

According to Nadia Gosselin, a professor in the Department of Psychology at the Université de Montréal and scientific director of the Centre for Advanced Studies in Sleep Medicine, this time change is important to consider because it can disrupt the body's functioning.

"Our bodies and eyes are very sensitive to light," said Gosselin. "For some people, this variation affects their energy level and mood. It should be noted that this alteration is caused more by less exposure to the sun."

Although the semi-annual time change is a contested practice in Quebec, it can still have some benefits. If daylight saving time were maintained, the sun would rise at a late hour -- sometimes even after 8:00 a.m. -- which would be more difficult for the body.

"It's really the morning light that helps the body synchronize with the day and gives it a good wake-up signal," said the scientific director. "It's important, so getting back to normal time can help many people -- especially those who wake up earlier -- to get that light."

That said, most people adapt easily to this disruption in their schedule. Only a minority of people will report problems that last for more than a week. This is particularly true for the elderly, whose biological clock is more sensitive to disruptions. Conversely, others will show little or no effect from this setback, such as adolescents and young adults.

"For teenagers, there should be no problems because they are used to going to bed late and they have a biological preference to get up late. So this time change will fit in with their biological schedule," said Nadia Gosselin.

This report by The Canadian Press was first published in French on Nov. 5, 2022. 

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This article was produced with the financial support of the Meta and Canadian Press News Grants.