If the clocks stop changing, sleep researchers want winter mornings back

Under permanent daylight saving time, the latest winter sunrise in Toronto would come at 8:51 a.m. In Calgary it would be 9:40 a.m. Under standard time, both arrive an hour earlier.

That hour is the heart of an analysis in the Canadian Medical Association Journal, led by Raymond Lam. If Canada ends the twice-yearly clock change, the authors argue, it should keep standard time. Morning light helps set the body clock, which shapes sleep and mood. They cite estimates that seasonal affective disorder affects 1–3% of Canadians, and that up to 15% have milder seasonal shifts in mood and sleep.

The opposite choice is gaining ground. Yukon adopted permanent daylight saving time in 2020, British Columbia followed in March 2026, and in July the US House passed a bill to make daylight saving time permanent.

This is a policy argument, not a new study measuring how people sleep under each system, and the details here come from reporting on the paper. The authors acknowledge what their choice costs: standard time brings earlier winter sunsets.