On the night of October 26 to 27, residents of about 40 percent of the world’s countries will set their clocks back for winter time. Many will be looking forward to an extra hour of sleep before the workweek begins on Monday.
Scientists aren’t so optimistic. That seemingly harmless extra hour can trigger health problems, disrupt sleep, and increase the number of traffic accidents.
Recently the British Sleep Society urged an end to the twice-yearly clock changes. They want to stop the practice of moving clocks forward one hour at 1:00 AM on the last Sunday in March and back one hour at 2:00 AM on the last Sunday in October.
Different countries adopted the practice at different times, often arguing it would boost productivity by making better use of daylight. It was also supposed to save electricity — a hope later shown to be unfounded.
The British Sleep Society is calling for a permanent return to standard time (Greenwich Mean Time) and cites new research on the harms caused by changing the clocks.
What Are the Risks?
Losing an hour of sleep when clocks spring forward typically leaves people more fatigued. It isn’t surprising that the risk of fatal traffic accidents rises by an average of six percent after the spring switch to daylight saving time.
Research also links the clock change to a short-term increase in cardiovascular events, suicidal behavior, and mortality in the days immediately following the transition.
Recent studies have found that people living on the western edge of time zones — where solar time and biological clocks are more out of sync — face higher risks of leukemia, stomach, lung, and breast cancers. Because that mismatch resembles the effects of springing forward, some scientists worry that daylight saving time could have similar long-term consequences.
The British Sleep Society emphasizes that a good night’s sleep is essential for health. Forced changes like the switch to and from daylight saving time harm sleep quality, the society says, and those impacts can ripple into other areas of health.
Researcher Eva Winnebeck of the University of Surrey noted, “Daylight saving time forces all of us to get up and go to work or school an hour earlier. That means that during seasons with fewer daylight hours, particularly in the fall, most of us have to wake up and commute in the dark.” The society argues that natural morning light is crucial for synchronizing our biological clocks, improving sleep, and supporting overall health.
“Some even advocate for daylight saving time to be in effect year-round, but we consider that a misguided idea,” said Professor Malcolm von Schantz of Northumbria University. There simply isn’t enough daylight to ‘save’ during the winter months. When choosing between natural light in the morning and natural light during the day, the society favors morning light.
The British Sleep Society published its recommendations in the Journal of Sleep Research.
