Canadian health researchers are urging the country to choose permanent standard time over permanent daylight saving time if it decides to end the twice-yearly clock change, warning that darker winter mornings could harm sleep and mental health.
The analysis, conducted by Canadian health researchers, focuses on the potential consequences of locking the clock to daylight saving time year-round — a proposal that has gained traction in various jurisdictions seeking to eliminate the seasonal time shifts. According to the researchers, such a move would push sunrise later during winter months, depriving people of morning light that is critical for regulating the body's internal clock.
Morning light exposure is a key signal for the human circadian system, which governs sleep-wake cycles, hormone production, and mood. When mornings remain dark, the body's natural rhythms can fall out of sync with the external environment, leading to sleep disturbances and a range of mental health concerns. The researchers specifically point to the winter months, when daylight is already scarce in northern latitudes, as the period of greatest risk.
The warning comes amid ongoing debates in Canada and elsewhere about whether to abolish the practice of changing clocks twice a year. Permanent daylight saving time has been proposed as a way to preserve evening daylight, but the Canadian analysis suggests that this approach could backfire by creating darker mornings that disrupt sleep and exacerbate mental health challenges.
Permanent standard time, by contrast, would keep winter mornings brighter and better aligned with the body's natural rhythms, according to the researchers. They argue that this option should be prioritized if the clock change is eliminated, as it would support healthier sleep patterns and reduce the risk of mood disorders associated with insufficient morning light.
The findings add to a growing body of evidence linking light exposure, circadian health, and mental well-being. Sleep experts have long cautioned that abrupt changes to the clock can disrupt sleep, but the Canadian analysis extends the concern to permanent daylight saving time, which would lock in late sunrises during winter.
For residents of northern countries like Canada, where winter days are short and sunlight is limited, the implications could be significant. Darker mornings may make it harder to wake up, reduce alertness, and contribute to seasonal affective disorder and other mental health conditions. The researchers emphasize that the choice between permanent standard time and permanent daylight saving time is not merely a matter of convenience but a public health decision with real consequences for sleep and mental health.
As policymakers weigh the future of daylight saving time, the Canadian analysis provides a clear recommendation: if the clock change is to be abolished, permanent standard time is the safer option for sleep and mental health. The researchers urge decision-makers to consider the health impacts of darker winter mornings before adopting permanent daylight saving time.
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