TIME YOU GO TO BED COULD HELP TO CUT CHANCES OF HEART DISEASE

▶ UK survey links bedtime of between 10pm and 11 pm with better cardiovascular health

We all know the importance of a good night’s sleep, but the time you go to bed could also be crucial, scientists say.

Going to sleep between 10pm and 11pm is associated with a lower risk of developing heart disease compared with other bedtimes, research found.

Staying up into the small hours was particularly bad.

The study found that compared to falling asleep between 10pm and 10.59pm, there was a 25 per cent higher risk of cardiovascular disease doing so at midnight or later.

There was a 12 per cent greater risk for 11pm to 11.59pm, and a 24 per cent increased risk for falling asleep before 10pm, according to the study.

Further analysis suggested the association with increased cardiovascular risk was stronger in women, with sleep onset before 10pm remaining significant only for men.

While numerous analyses have investigated the link between sleep duration and cardiovascular disease, the relationship between sleep times and heart disease is underexplored, researchers said.

“The body has a 24-hour internal clock, called circadian rhythm, that helps regulate physical and mental functioning,” said study author Dr David Plans, of the University of Exeter in the UK.

“While we cannot conclude causation from our study, the results suggest that early or late bedtimes may be more likely to disrupt the body clock, with adverse consequences for cardiovascular health.”

This study examined the association between objectively measured, rather than self-reported, sleep time in a large sample of adults.

The survey included 88,026 people in the UK Biobank study recruited between 2006 and 2010. The average age was 61 years, with a range between 43 to 79 years, and 58 per cent were women.

Researchers collected data on sleep and waking-up time over seven days using a device worn on the wrist.

During an average follow-up of 5.7 years, 3,172 participants (3.6 per cent) developed cardiovascular disease, according to the study published in European Heart Journal – Digital Health, by the European Society of Cardiology.

The study said the incidence was highest in those with sleep times at midnight or later and lowest in those who went dozed off between 10pm and 10.59pm.

The researchers analysed the link between falling asleep time and cardiovascular events after adjusting for age, sex, sleep duration, sleep irregularity, self-reported chronotype (early bird or night owl), smoking status, body mass index, diabetes, blood pressure, blood cholesterol and socioeconomic status.

“Our study indicates that the optimum time to go to sleep is at a specific point in the body’s 24-hour cycle and deviations may be detrimental to health,” Dr Plans said.

“The riskiest time was after midnight, potentially because it may reduce the likelihood of seeing morning light, which resets the body clock.”

He said the reasons for the observed stronger association between going to sleep time and cardiovascular disease in women is unclear.

“It may be that there is a sex difference in how the endocrine system responds to a disruption in circadian rhythm,” Dr Plans said.

While the findings do not show causality, sleep timing has emerged as a potential cardiac risk factor – independent of other risk factors and sleep characteristics.

“If our findings are confirmed in other studies, sleep timing and basic sleep hygiene could be a low-cost public health target for lowering risk of heart disease.”

Regina Giblin, senior cardiac nurse at the British Heart Foundation, said going to sleep between 10 and 11pm could be the sweet spot for most people to keep their heart healthy.

“However, it’s important to remember that this study can only show an association and can’t prove cause and effect.”

There is a 12% greater risk for 11pm to 11.59pm, and a 24% higher risk for falling asleep before 10pm, the study shows