The evidence shows that time change is bad for our health and that we should maintain permanent standard time.
by Rébecca Robillard. Originally published on Policy Options
November 23, 2024
(Version française disponible ici)
The practice of changing the clocks is a historical legacy that no longer has any raison d’être. It’s not a question of opinion or personal preference, but of public health and scientific evidence.
In light of the public consultations on time change that run until December 1, Quebecers have a responsibility to get informed and fully understand the multiple impacts of time change. The scientific consensus is clear: it’s in the best interests of everyone’s health to abolish time change and adopt permanent standard time. We have a duty to back up our position with facts, and to prioritize the well-being and health of all our fellow citizens.
The impacts of time change
The shift to and from daylight time causes abrupt disruptions to our sleep-wake cycle, amplifying the chronic sleep deprivation affecting many of us.
In spring, when we turn the clocks forward, we lose an hour of sleep. Because daylight time increases the amount of light at the end of the day throughout the summer, we tend to go to bed later, while getting up at the same time. This means we lose an average of 20 to 30 minutes of sleep. Given the active role that sleep plays in the proper functioning of the body and brain, the time change has adverse consequences on several aspects of our health. However, the effects of time change are not limited to sleep loss or gain.
The biological clock, a complex and delicate system that regulates most of the body’s functions, is synchronized primarily by the light-dark cycle. This clock co-ordinates hormone secretion, insulin regulation, heart rate, blood pressure, metabolism, body temperature and even gene expression, to give just a few examples. All these mechanisms, essential to the proper functioning of the body and brain, are strongly modulated by the time at which we are exposed to light.
For the majority of humans, the biological clock cycle covers a period of just over 24 hours. As a result, the regulation of our circadian rhythms (the daily biological variations that enable the body to function properly) tends to lag behind. Morning light and darkness at the end of the day generate a cascade of physiological reactions that constantly resynchronize the biological clock, realigning our circadian rhythms with the actual length of a day. This enables our bodies and brains to function optimally.
However, the time change creates a mismatch between the biological clock, the schedule dictated by social constraints and the light-dark cycle. Evidence shows that this mismatch persists until we return to standard time, as the biological clock is unable to adjust to daylight time.
Controlled laboratory studies have shown that this type of shift notably increases heart rate, blood pressure and inflammation, as well as the disruption of metabolism, immune system, mood and several intellectual functions. It’s not surprising, then, to see a population-wide increase in heart attacks, strokes, infections and immune diseases, digestive problems, pregnancy and childbirth complications, and a deterioration in mental health as a result of the time change.
Daylight time has also been associated with a six-to-30 per cent increase in the risk of road accidents, as well as an increase in work-related accidents and serious injuries. Many of these effects persist up to several weeks or even months after the day of the time change, as some biological clocks take time to adjust. Finally, the lag created by the spring time change is compounded by the natural decrease in sunlight hours, which begins well before the return to standard time in early November, further widening the gap between solar and social time.
Sometimes invisible, often uneven effects
Some people do not consciously feel the physiological effects of the time change. Although not all of these effects are perceptible, they nonetheless alter body and brain function, increasing health risks.
What’s more, it’s crucial to note that the time change doesn’t affect us all in the same way. The impact is greater for the elderly, children and teenagers, people with chronic illnesses and those living in the western portion of their time zone. Genetic predispositions also mean that some people have more difficulty coping with the effects of time change. Decisions concerning the practice of time change should therefore aim for equity in health and well-being for all Quebecers.
Why permanent standard time, and not daylight time?
Keeping permanent daylight time could have even more serious impacts than maintaining the practice of time change. In winter, when the sun rises later, our biological clock is also delayed. This forces us to get up before our bodies are ready to do so. If we adopted permanent daylight time, it would be even worse: most of us would have to start school or work before sunrise for a third of the year.
By widening the gap between our biological clock and the social and environmental clocks, switching to permanent daylight time would risk increasing sleep deprivation, infections, high blood pressure, cardiovascular complications, diabetes, cholesterol problems, neurological disorders, mental health problems and accidents, in addition to causing a general decline in performance.
After switching to permanent daylight time, the USA and Russia observed public dissatisfaction from the very first winter, as well as an increase in stress, health problems and accidents. This prompted them to backtrack. In particular, the maintenance of year-round daylight time aggravated winter depression among teenagers, a situation that was alleviated after the adoption of permanent standard time.
What the Quebec government’s public consultation refers to as “winter time” is in fact standard time, as naturally defined by the sun. Permanent standard time would maximize the synchronization between the biological clock and the light-dark cycle. This is the best option for health, safety and productivity.
If, in spite of scientific evidence, the government decides to retain current time-change practice, its negative impacts could be mitigated by making two changes to the transitions. First, time change should occur closer to the equinoxes to limit the time lag with the solar cycle. Second, it should be done on Friday night to lengthen the weekend adjustment period before most people return to school or work.
The evidence overwhelmingly suggests that it is in the best interests of collective well-being and public health to adopt standard time on a permanent basis. Quebec has the opportunity to show the rest of the world that we dare to question and innovate to improve our quality of life and protect the health of our people.
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This article first appeared on Policy Options and is republished here under a Creative Commons license.