Permanent standard time offers greater health benefits than daylight saving time, study finds

Circadian alignment and health impacts

A research review published in the Canadian Medical Association Journal concludes that permanent standard time is healthier for human biology than permanent daylight saving time. The investigation was conducted by a research team led by Raymond Lam at the University of British Columbia in Vancouver. While public surveys frequently show popular backing for permanent daylight saving time due to prolonged evening light, chronobiology findings indicate that later solar time corresponds with reduced sleep duration, lowered workplace productivity, and poorer student performance. Morning sunlight serves as the primary environmental cue to align the biological clock with the 24-hour solar cycle, whereas prolonged evening light delays internal sleep rhythms. Large professional sleep and chronobiology associations recommend establishing permanent standard time whenever seasonal clock changes are eliminated.

Morning darkness and seasonal depression

The analysis examines how permanent daylight saving time forces school and work commutes to occur in morning darkness throughout winter months. Co-author Patrick Baylis described the tension between public preference and physiological consequences.

The appeal of permanent daylight saving time is easy to understand: people appreciate having daylight last longer after work or school. However, these evening benefits are countered by findings that link later solar time to less sleep, lower productivity, and poorer academic performance.

Darker winter mornings create documented strain for individuals suffering from winter depression linked to seasonal affective disorder. Public health estimates indicate that seasonal affective disorder affects 1% to 3% of Canadians, while another 15% experience milder seasonal disruptions in mood, sleep patterns, appetite, and energy levels.

Historical reversals in the United States, Russia, and Chile

Historical precedents evaluated in the study show that several nations previously established permanent daylight saving time before quickly abandoning the policy. During the 1974 energy crisis, the United States introduced permanent daylight saving time but repealed the system within a year following public dissatisfaction over dark winter mornings and child safety hazards on morning school commutes. Russia enacted permanent daylight saving time in 2011 and reversed the decision in 2014. Chile adopted permanent daylight saving time in 2015 and subsequently repealed the measure.

Policy recommendations and regional debates

Multiple Canadian provinces are currently evaluating legislative proposals to end biannual clock adjustments, mirroring long-running policy discussions in Germany and across the European Union. In the United States, Donald Trump has publicly advocated for permanent daylight saving time, arguing that additional evening sunlight benefits recreational golfers. Co-author Alexandra Choi emphasized that any jurisdictions choosing daylight saving time must enact public health protections well ahead of winter.

Should governments decide on permanent daylight saving time, they must plan for the consequences before the first winter, from safer morning commutes to work and school and flexible start times to monitoring sleep, mental health, and injury risks.

The review also cited related scientific contributions from Jorge Mira at the University of Santiago de Compostela and José María Martín-Olalla at the University of Seville.