An irregular sleep pattern increases the risk of stroke and heart attack, a British study has found

Not sticking to a set time for going to bed and waking up increases the risk of stroke, heart attack and heart failure by 26%, even for those who get a full night’s sleep, the most comprehensive study in its history suggests. kind.

Previous studies have focused on the link between sleep duration and health outcomes, with people advised to get between seven and nine hours of shut-eye per night.

That advice still applies. But researchers are increasingly focusing on sleep patterns, and in particular the impact of irregular sleep – defined as variations in the time a person goes to sleep and wakes up.

The new study found that irregular sleep – going to bed and waking up at different times each day – was “strongly associated” with a higher risk of serious adverse cardiovascular events. Even getting eight hours of sleep was insufficient to offset the harmful effects of constantly varying bed and wake times, experts said.

The research, published in the Journal of Epidemiology and Community Health, the UK Biobank study included 72,269 people aged 40 to 79 years. It hasn’t been determined exactly how close you need to be to the same bedtime and wake-up time – just that the further away you are, the greater the risk of damage.

The lead author, Jean-Philippe Chaput, from the University of Ottawa, said: “We should aim to wake up and go to sleep at the same time every evening and every morning, including weekends, within 30 minutes. Within an hour of the same time is good, but less good than 30 minutes, and even better is to have no variation.

“More than an hour difference every night and every morning means irregular sleep. This can have negative health consequences. The closer you are to zero variation, the better.

“No one is perfect all year round, and not having a regular sleep pattern one or two days a week isn’t going to kill you. But if you repeatedly sleep irregularly, five or six days a week, then it becomes chronic, and that’s a problem.”

Chaput said waking up at the same time every day was more important than going to bed at the same time. “Waking up at a different time every morning messes with your internal clock, and that can have adverse health consequences,” he said.

“If you need to catch up on the sleep you missed during the week at the weekend, then going to bed earlier is better than sleeping in – you should still try to wake up at the same time, even on Saturday and Sunday.”

In the study, participants wore an activity tracker to record their sleep for seven days, after which experts calculated a sleep regularity index (SRI) for each person.

The score recorded daily variability in bedtime, wake-up time, sleep duration and waking during the night, with people given a score ranging from 0 (very irregular) to 100 (completely regular sleep-wake pattern). .

Participants were classified into an irregular sleep group (SRI score lower than 71.6), moderately irregular sleep group (SRI between 71.6 and 87.3) or normal sleep group (SRI score higher than 87.3). People were then followed for eight years.

Even after taking into account factors that could influence the results, irregular sleepers were 26% more likely to have a stroke, heart failure or heart attack than those who sleep regularly, the study found. Moderately irregular sleepers were 8% more likely to do this.

Researchers found that the SRI score was a continuous measure, with people’s risk of heart attack and stroke increasing the more irregular their sleep patterns were.

The recommended amount of sleep for 18 to 64 year olds is seven to nine hours per night, and seven to eight hours for people aged 65 and over.

The study found that a greater proportion of regular sleepers (61%) met the recommended sleep quota than irregular sleepers (48%). But this made no difference to the heart health of irregular sleepers, who had the same higher risk of stroke and heart attack even if they got enough sleep.

In contrast, moderately irregular sleepers saw their risk decrease if they got enough sleep.

This was an observational study and as such could not establish cause and effect, and the researchers acknowledged several limitations to their findings.

But they concluded that the findings suggest that irregular sleep was strongly associated with a risk of serious cardiovascular events in adults, regardless of whether or not recommended sleep quotas were met.

“More importantly, our results suggest that sleep regularity may be more relevant than adequate sleep duration in modulating the risk of major cardiovascular events.”