Permanent Daylight Saving Time May Harm Health, Sleep Expert Warns
A sleep and circadian rhythm expert cautions that permanent daylight saving time would push sleep later and worsen health, favouring permanent standard time instead.
As the debate over ending the twice-yearly clock change continues, a sleep and circadian rhythm researcher is cautioning that making daylight saving time permanent could carry significant health costs.
Kenneth Wright, a Professor of Distinction in the Integrative Physiology department at the University of Colorado Boulder and director of its Sleep and Chronobiology Laboratory, studies the health and safety consequences of insufficient sleep and circadian misalignment. His assessment places permanent standard time as the healthiest option, the current switch between the two as a middle path, and permanent daylight saving time as the worst of the three.
The core of the argument rests on how light regulates the body's internal clock. Morning sunlight helps synchronise circadian rhythms and sleep timing to the 24-hour day, nudging people earlier. Without it, most people drift later, out of step with early school start times and work schedules. Permanent daylight saving time would mean darker mornings and brighter evenings, delaying sleep and circadian rhythms — a shift linked to poorer health outcomes at both individual and population levels.
Wright also points to practical safety concerns. Later sunrises would send children to school and night-shift workers home in darkness, and push ordinary morning commutes into low light, conditions he says would increase accidents during morning hours.
He notes that the sun itself does not change with these decisions; what changes is when the clock is set and, consequently, when work and school begin. Under current federal law, he adds, the country could adopt permanent standard time without any legislative change.
If the status quo of switching clocks is retained, Wright suggests steps to soften its effects. Moving the transition from Sunday morning to the Friday-to-Saturday window, for instance, would give people an extra day to adjust over the weekend, similar to recovering from jet lag. He argues that such measures, alongside other strategies, could reduce the safety and well-being impacts of the shift.
On the broader question of health, particularly for children, Wright describes the evidence as unanimous: if a change is to be made, permanent standard time is the healthier and safer long-term choice.