This weekend, millions of people pushed their clocks back an hour to mark daylight saving time—but at the same time, they have thrown their internal body clock off kilter, raising the risk of heart disease, experts have warned.
Staying up late, eating at random times and being exposed to artificial light before bed can also increase the risk of obesity, type 2 diabetes, and high blood pressure—all of which put added stress on your heart.
‘Circadian rhythms are produced by the body’s natural 24-hour internal clock that regulates a multitude of biological processes like sleep, wakefulness, hormone release digestion and body temperature,’ Dr Kristen Knutson, professor of neurology and statement co-author explained.
And whilst everyone’s circadian rhythm is slightly different, we broadly follow a pattern that is dictated by daylight hours, with neurons activating genes and proteins throughout the body in a regular cycle.
‘But regular interruptions to the body clock are much more than simple inconveniences—like staying up too late or waking up too early.
‘These disruptions may trigger adverse health effects in several ways,’ Dr Knutson, an expert in sleep and heart health, warned in the statement published today in the American Heart Association’s flagship journal, Circulation.
‘Therefore aligning our daily behaviours, when we sleep, eat and move, with our internal clocks is imperative to support optimal cardiometabolic health.’
Beyond disrupting the body clock, staying up an extra hour, waking up early to finish the work you didn’t get done the night before or eating at random times can also affect heart health.
Experts from the American Heart Association say the disruption that eating at random times, staying up late and light, cause to the body’s natural clock, known as the circadian rhythm, could have serious heart consequences (Stock image)
Top scientists have called for an end to Daylight Saving Time (DST), amid fears it fuels a rise in cancer, traffic accidents and suicide
For example, if a night owl has to get up earlier than usual to catch a flight, they will be awake during what’s known as their biological night, interrupting their natural circadian rhythm.
Even if they attempted to counteract this by going to bed earlier, this shift in sleep time can disrupt circadian rhythms, increasing the risk of social jet lag, which can lead to a subtle shift in blood pressure, hormone secretion and metabolism which all raise heart attack risk.
This phenomenon should also be guided by an individual’s chronotype—a person’s internal timing for sleep and activity—Dr Knutson suggested, as being a ‘morning person’ or ‘night owl’ can affect how we respond to light, meals and exercise, meaning that it’s not a one size fits all approach.
Light pollution in the bedroom could also raise sleepers’ risk of heart disease, research has long claimed.
Exposure to light at night, from electronic devices, street lamps or poorly drawn curtains is never good for your sleep.
Now scientists say the disruption that light causes to the body’s natural clock, suppressing melatonin and delaying sleep onset, could have deadly consequences.
This theory is supported by numerous studies, the largest of which analysed data from over 89,000 people and found that those who had the brightest nights had a 23 to 56 per cent higher risk of developing cardiovascular disease than those with dark nights.
An example of a person in the highest light exposure group may be someone who turned on overhead lights for just one hour between midnight and 6am, when their body was biologically in its sleep stage.
Dr Knutson adds that because the body continue to react to artificial light after it has been switched off, even short exposures can affect circadian rhythms.
This increased risk of heart disease is often independent of sleep duration of efficacy—or even a genetic predisposition to poor heart health—pointing to a disruption in circadian rhythms as the key driver of the results.
Eating late at night or having irregular meal times can have a similar effect—misaligning the circadian rhythms governing organs like the liver and pancreas, contributing to blood sugar spikes or drops, and weight gain.
Disruption to circadian rhythms have also been shown to impair glucose tolerance, increasing the risk of type 2 diabetes, high blood pressure and abnormal heart rhythms, due to conflicting signals between the brain and heart.
‘Although circadian rhythms play an important role in keeping us healthy, they are often overlooked in everyday medical care.
‘It’s important to realise what these disruptions can do to our body and how to lessen the impact,’ Dr Knutson says.
‘Everyone has an internal clock, and it’s time we start listening to it.
‘Simple changes, like going to bed and waking up at the same time every day, eating meals earlier and getting morning sunlight, may make a meaningful difference in your heart and metabolic health.’
Light pollution in the bedroom could raise sleepers’ risk of heart disease, research claims (Stock image)
Dr Knutson recommends everyone making an effort to maintain consistent sleep and wake times—to help synchronise the body’s internal clock and support heart health—getting outside in natural light in the morning to help reinforce healthy rhythms and implementing regular exercise as a secondary synchroniser.
Whilst the researchers acknowledged more work is needed to fully understand causality and help develop personalised interventions, they hope new technologies—like wearable trackers—may soon make it easier.
Alarming data last year revealed that premature deaths from cardiovascular problems generally, such as heart attacks and strokes, had hit their highest level in more than a decade.
The Daily Mail previously highlighted how the number of young people, under 40, in England being treated for heart attacks by the NHS is on the rise—with modern lifestyles throwing off our biological timers and increasing our susceptibility to different conditions.