Canadian researchers argue that permanent standard time is better for our biological clocks, sleep and mood, while permanent daylight saving time could disrupt our natural rhythms.
As the return to standard time approaches, the debate over whether we should change our clocks twice a year is heating up once again. During the night between Saturday, October 24, and Sunday, October 25, clocks will be turned back by one hour at 3 a.m. The change has long divided public opinion between “early birds,” who welcome daylight in the morning, and “night owls,” who prefer brighter evenings.
But which side is right? And if Europe eventually decides to abolish the seasonal clock change and adopt a single time system throughout the year, should it choose standard time or daylight saving time?
According to a recent analysis published in the Canadian Medical Association Journal (CMAJ), scientific evidence largely supports the permanent adoption of standard time.
Raymond Lam, one of the researchers involved, explains that eliminating the clock change would solve one problem but create another: deciding which time system is best for our health and daily lives. He argues that standard time is the preferable option because morning light plays a crucial role in regulating our biological clocks, sleep patterns and mood.
Why Morning Light Matters
Both options have advantages and disadvantages. Permanent daylight saving time would provide brighter evenings, allowing people to enjoy outdoor activities, socialise for longer and potentially benefit businesses and the economy. However, it would also mean later sunrises, forcing many people to travel to school or work in darkness during the winter months.
Scientists warn that this shift could have consequences for human health. Morning light helps synchronise the body’s internal clock, known as the circadian rhythm, with the natural 24-hour day. By contrast, exposure to light in the evening tends to delay this biological clock.
As a result, permanent daylight saving time could make it harder for the body to maintain a healthy sleep-wake cycle, particularly during winter, when daylight is already limited.
Ralph Mistlberger, a professor of psychology at Simon Fraser University in Vancouver, emphasises that the human body needs morning light to remain properly synchronised with the natural environment. Permanent daylight saving time would delay exposure to this light by one hour, making winter mornings even darker.
Researchers suggest that this disruption could negatively affect sleep quality and mood. For this reason, several leading organisations specialising in sleep and chronobiology recommend permanent standard time rather than permanent daylight saving time.
Lessons from Other Countries
International experience also provides reasons to be cautious about adopting daylight saving time throughout the year.
In the United States, permanent daylight saving time was introduced in 1974 during the energy crisis. However, the measure was abandoned less than a year later following widespread public opposition. Many people complained about dark winter mornings, while concerns grew over children having to travel to school before sunrise.
Russia followed a similar path in 2011, adopting permanent daylight saving time before reversing the decision in 2014 after public dissatisfaction. Chile also abandoned its experiment with permanent daylight saving time following a trial in 2015.
These examples illustrate the difficulties of finding a time system that satisfies everyone, especially when public preferences for brighter evenings conflict with the body’s need for morning light.
A Choice Between Lifestyle and Health
The debate over standard time and daylight saving time is about more than convenience. It also raises questions about how modern lifestyles interact with our natural biological rhythms.
While brighter evenings may benefit social life and leisure activities, researchers argue that morning daylight is essential for maintaining a healthy circadian rhythm. From this perspective, permanent standard time appears to offer greater benefits for sleep and overall well-being.
As discussions about abolishing seasonal clock changes continue in Europe and elsewhere, scientific evidence may play an increasingly important role in shaping future decisions.
Although no single solution will satisfy everyone, researchers suggest that keeping standard time throughout the year could be the best option for human health. For those who prefer longer, brighter evenings, this may be disappointing news. However, when it comes to our biological clocks, science appears to favour the early birds.
