On the night of Saturday, October 28 to Sunday, October 29, at 4:00 a.m., we’ll set our clocks back one hour — returning to standard time.
The debate over whether we should keep changing the clocks has been going on for decades. Meanwhile, researchers have long warned that the shift can disrupt circadian rhythms and harm overall health.
The Biological Clock and Stroke
Professor Russell Foster of the University of Oxford, a leading expert on circadian rhythms, says the first thing to suffer when we switch back to standard time is our sleep. But that’s not all.
Our biological clock regulates daily rhythms. It affects how clearly we think, when our digestive system is ready to process food, when our muscles are strongest, and more. Circadian rhythms also govern metabolism, body temperature, and hormone levels.
During the day, sunlight prompts the brain to send wakefulness signals that keep us alert and active. At night, this system, which can be compared to the intricate mechanism inside an antique clock, triggers the production of melatonin—a hormone that promotes sleep.
Changing the clock disrupts those processes. Foster says sleep disturbances combined with circadian disruption can trigger strokes.
There is also a risk of elevated blood pressure, which can lead to clot formation and blockages in the arteries that supply blood to the brain. As a result, brain cells begin to die, causing the characteristic signs of a stroke, such as slurred speech and weakness on one side of the body.
Foster says the clock change isn’t particularly dangerous for healthy people. But for high-risk groups, the switch back to standard time can add extra strain on the body.
A British study from 2016 found that in the two days following the clock change, hospitalizations for strokes increased by 8 percent, with the greatest risk affecting people aged 65 and older.
Heart Attacks
Dr. John O’Neill of the University of Cambridge, another leading circadian expert, says the stress of the clock change can raise the risk of heart attacks.
But O’Neill adds that switching to standard or daylight saving time has only a minor health impact — similar to crossing time zones. “If circadian rhythms are systematically disrupted, for example by shift work, then it is indeed harmful to health,” he said.
Research from the University of Colorado found a significant link between clock changes and more heart attacks. During the spring switch to daylight saving time, they recorded a 24 percent increase in heart attacks; the increase was smaller when switching back to standard time, according to the Daily Mail.
Depression
The clock change and disrupted sleep can affect mental as well as physical health.
A 2018 study by a team from the University of Glasgow, published in The Lancet Psychiatry, found that disruptions to the biological clock are linked to depression and bipolar disorder.
In addition, a 2020 study by Italian researchers, published in the Journal of Sleep Research, found that lack of sleep is a key cause of low mood.
Alzheimer’s Disease
Some experts say moving the clock forward or back can worsen symptoms of Alzheimer’s disease. In his book “Life Time,” Foster lists symptoms such as confusion, anxiety, aggression, and a tendency to wander. These symptoms often appear in the evening or early night and can get worse around the clock change.
Accidents
A Swiss study found that the extra hour in bed after the switch to standard time is associated with a rise in car accidents. Drivers also have to adapt to longer, darker evenings.
The team analyzed thousands of traffic accident cases from 2018 to 2020 and found that before the fall clock change, a quarter of car accidents occurred between 4:00 p.m. and 7:00 p.m. However, after the switch to standard time, that proportion rose to a third of all accidents during that time frame.
How to Ease the Transition to Standard Time
Go to bed at least half an hour earlier for three days before the clock change. Eat healthily and limit alcohol. Take regular walks or exercise outdoors to help the transition. Aim for calm and avoid stress. Monitor your health closely during these days, especially if you have heart conditions or hypertension.
