Millions of people this weekend will set their clocks forward to mark the beginning of daylight saving time, raising their risk of serious health complications, including heart attacks.
On March 9, every state except Arizona and Hawaii will ‘spring forward’ by one hour, giving people less sleep but extending daylight hours for the spring and summer.
Daylight saving time (DST) has been going on for more than a century and was originally intended to provide more daylight time to extend the workday while conserving fuel and power – working with the sun in sky meant burning less fuel.
The cycle ends the first Sunday in November, leading to earlier sunsets and more hours of darkness – and the inevitable mood decline that comes with less sunlit hours.
But while March’s extension of sunshine is good for the mood, a loss of an hour when the clocks initially change has been known to set off a cascade of health effects, including fatigue and poor sleep, as well as a greater risk of heart attack and stroke.
Adapting to a new sleep schedule throws people off their normal sleep-wake rhythm because of a disruption to their circadian rhythm – the body’s internal clock. The rhythm is finely attuned to environmental cues like sunlight, which stimulates wakefulness.
Even just a one hour change is enough to disrupt people’s internal clock and can worsen symptoms of depression, anxiety and grogginess.
In addition, daylight saving time is linked to an increased risk of heart attack and a six percent increase in fatal car accidents.
The first day or two after DST are the worst. The increased risk of all the above lessen as people become more accustomed to the lost hour of sleep
Dr Helmut Zarbl, director of Rutgers University’s Environmental and Occupational Health Sciences Institute, told DailyMail.com the small change throws every cell in the body off and ‘they don’t do what they’re supposed to be doing.’
The Monday morning after changing the clocks, which occurs at 2 am on Sunday, might be a bit sleepier than usual.
A 2023 study by the American Psychological Association found the average person gets 40 minutes less sleep on the Monday after DST compared with other nights during the year.
The body performs best when on a consistent sleep schedule, but springing forward an hour tricks the body’s internal clock into thinking it isn’t bedtime because it’s brighter later into the evening.
Quality sleep and getting enough of it, however, is crucial to good physical and mental health.
It mitigates the risk of a whole host of chronic illnesses, improves memory and learning ability, and helps maintain a healthy weight.
Adjusting to daylight saving takes time, and for some people it can take days.
But before the adjustment, the time change can potentially wreak havoc – and studies have linked the effects for more than a decade.
A 2014 study in the journal Interventional Cardiology found a 24 percent increase in heart attacks on the Monday following the Spring switch to daylight saving time.
Similarly, Finnish scientists behind a 2016 study presented by the American Academy of Neurology found the overall rate of ischemic stroke was eight percent higher during the first two days after DST.
Meanwhile, daylight saving time also has a negative impact on people’s mental health and productivity.
UK researchers reported in 2014 that ‘self reported life satisfaction deteriorates’ after the time change.
A 2022 study in the journal Health Economics found sleep disturbances caused by DST led to a 6.25 percent increase in the suicide rate and a 6.6 percent increase in the combined death rate from suicide and substance abuse.
The time change has such an impact on people because it messes with the body’s cells.
Every cell in the body has its own circadian clock synchronized to the ‘master’ clock in the brain, which takes its cues from light and other factors such as social interactions and meals.
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Dr Zarbl told DailyMail.com: ‘So what happens if we disrupted the central organizer or the circadian timekeeper? Basically, all the cells suddenly don’t know what time it is, and they don’t do what they’re supposed to be doing.
‘That’s important, because circadian rhythm controls all of our bodily functions – sleep, obviously, blood pressure, hormones, repairing damage to the body, healing, every function your body [does] is tied to the clock.’
Experts have likened the effects of daylight savings to those of jetlag. Flying across time zones can cause people to feel exhausted and moody the first couple of days, but those symptoms typically resolve themselves as the traveler is able to sync their sleep schedule with the new time.
Dr Zarbl said: ‘For several days, you feel terrible. That’s because you basically misaligned your clock from your biological cues, so the clock has to be reset completely. And that takes about a week.’
Luckily, there are measures you can take to smooth out the transition to a spring timetable, such as starting to eat meals 10 to 15 minutes earlier than usual in the days leading up to the time change.
Dr Zarbl said to ‘stop fighting it.’
He added: ‘Your brain also affects your circadian rhythm. So if you keep telling yourself, I’m tired, because I have to get up early, you’ll feel tired.’
