The dreaded changing of the clock is fast approaching: they return on October 27. It’s the moment when, despite that extra hour in bed, it feels like winter is coming to an end.
While an hour may not sound like much, it can have a big impact on our body clocks, which in turn can affect everything from digestion to blood pressure.
It has even been suggested that it would be better for our health if we abolished seasonal clock changes altogether.
Earlier this year, the American Academy of Sleep Medicine called for the elimination of biannual clock changes (one in spring and one in fall) because they cause a misalignment between the outside world and our body clock, or circadian rhythm. , which states that this has been ‘associated with risks to physical and mental health and safety, as well as risks to public health’.
The good news is that you can take steps to minimize such disruptions. And while you might not enjoy the prospect of dark nights, turning back the clock actually means we’re tuning into a more natural rhythm for our bodies – so you might find it easier than turning the clock back in the spring. (Unless you’re a natural morning person, who might find it harder – more on this later.)
Changing the clock twice a year can cause health problems such as increased heart rate and blood pressure, and has been linked to a spike in road accidents
Research has long shown that the ‘forward spring’ in March, which shifts us to British Summer Time, also known as daylight saving time, is linked to a sharp increase in health problems such as heart attacks and strokes, as well as hospital admissions for cardiovascular disease. fibrillation (an irregular heartbeat) in the following days.
And a 2019 review of seven previous studies by the University of Ferrara in Italy suggested that it is the disruption of our circadian rhythms and lack of sleep that leads to increased heart rate, blood pressure and inflammation levels.
The two clock changes per year have also been linked to an increase in road accidents, possibly because the disruption to sleep and our biological clock makes us feel ‘jet lagged’ and less alert.
For example, a 2020 study in the journal Current Biology found that car accidents increased by 6 percent after the turn of spring, while a 2018 RAC study of police data found that there was an increase in road accidents after the clock has gone back. ‘ to standard time in October.
‘Every cell of the body has its own clock,’ explains Dr Gisela Helfer, assistant professor of physiology and metabolism at the University of Bradford.
‘We also have a master clock in the brain – the suprachiasmatic nucleus (a small cluster of nerve cells) – and what it does is coordinate those rhythms, like a conductor in an orchestra.
Dr. Gisela Helfer, assistant professor of physiology and metabolism at the University of Bradford, says that while our brains quickly reset to clock forward or backward, our tissues and organs take longer to catch up, causing a kind of jet lag to get. a week or so
‘Every physiological process has a specific time when it works best. For example, when we sleep, we don’t eat, so we don’t need as many hormones to help us with digestion.
‘But when we wake up and our body expects to break our fast, we need insulin and the entire gastrointestinal tract needs to be prepared for the food to come. The problem is that our brains quickly reset to the new time, but our tissues and organs – such as our digestive system – have to catch up. Then we are out of sync for a week or two and then you experience the feeling of jet lag.’
A 2020 study in the Journal of Clinical Gastroenterology suggested that a disrupted circadian rhythm can cause stomach problems, especially constipation. The change in sleep patterns can also cause migraines or headaches.
To make the transition smooth, Dr. Kat Lederle, a sleep specialist at The London General Practice, suggests that in the six days before the clocks go back in the fall, we should go to bed perhaps ten minutes later each day. In the spring we should do the opposite.
“And do the same with meals and anything else that you can shift in small increments (for example, an exercise schedule),” she adds.
This helps because the timing of our meals and exercise sends signals to our body clocks that help them stay in rhythm. But why is a time change of just one hour so disruptive in the first place?
It has to do with changing light levels. Our bodies need darkness in the evening to prepare for sleep by producing melatonin, while light does the opposite.
Daylight directly signals the ‘master clock’ via special light receptor cells in the eyes, which the body uses as a signal to suppress melatonin, and also signals to the other clocks in our body that they should be in day mode.
While we may associate daylight saving time with bright summer mornings, the reality is that the clock changing in spring means it is actually darker when we wake up in April. While for most people, after the October change, it will initially be lighter when they wake up. Dr. Lederle explains, “From a light exposure perspective, it’s healthier if we keep standard time because it’s brighter in the morning.”
Clock changes can also affect us differently depending on our ‘chronotype’ – that is, our genetic tendency to be a lark (early to bed, early to rise) or an owl (late to bed, late to rise).
Larks appear to have more difficulty with the autumn shift than with the spring shift, according to a 2007 study by the University of Groningen, published in the journal Current Biology. But owls and humans who are not strongly one chronotype or the other find spring more difficult.
While you might think it’s better for the larks to have the evenings get dark earlier, they find it harder to adapt – possibly because they don’t feel the benefit of the lighter mornings, as they’re up before sunrise anyway . And they are unlikely to enjoy an extra hour in bed.
Others who likely won’t benefit from the extra hour of sleep at the fall clock change include anyone who shares their home with creatures whose brains don’t understand the concept of clock time: namely babies, dogs, and cats. That is, unless you also make an effort to gradually adjust light exposure and feeding times in advance.
Sleep specialist Dr. Kat Lederle suggests slightly adjusting your bedtime and mealtimes in the six days leading up to moving your clocks forward or back to minimize disruption to your ‘confused’ internal system.
The good news, however, is that babies adapt more quickly to ‘falling back’ (and wake up less during the night after the clocks go back), reported Sleep magazine in May last year – this may be because standard time is a better fit. with our natural circadian rhythm.
All of this has fueled the debate about whether we should stick with one all year round.
After all, summer time was only introduced in 1916 to make better use of the long summer days during the First World War and to save fuel (for example for coal-fired lighting).
In 2022, the American Medical Association called for an end to Daylight Savings Time, saying, “Staying with standard time has health benefits and allows us to end the biennial tug-of-war between our biological and alarm clocks.”
Dr. Lederle agrees: “When we suddenly have this mismatch, our brains get confused about what process to start and what to stop.
‘That’s when we see an increase in health problems – it affects heart rate, blood pressure and digestion, and in the long term we see a link between disrupted clocks and cancer risk plus fertility risk for women.’
And while some modern proponents suggest choosing one or the other—British Summer Time or Standard Time—”I would stick with standard time 100 percent,” says Dr. Lederle. ‘It doesn’t feel like it, because the days are shorter, but it is the healthier of the two. It’s better for our sleep.’
If we decided to permanently stick to British Summer Time, where the clocks are permanently set forward, sunrise on the shortest day of the year would be at 9.03am – and who wants that?