Going to bed during the ‘golden hour’ between 10pm and 11pm slashes the risk of developing heart disease, according to a major study.
Scientists found there is a link between bedtimes and heart attacks and stroke, particularly in women, with those who stay up late more at risk.
The study by the University of Exeter said going to bed after midnight may damage the heart as people are less likely to see morning light, disrupting the natural body clock.
It looked at data from more than 88,000 British adults between the age of 43 and 74.
Participants wore wrist trackers for a week which monitored what time they fell asleep and woke up, and also answered questions about their lifestyles.
This was compared with their medical records over five years detailing cases of heart disease, heart attacks, stroke and heart failure.
The research found the lowest rate of heart problems was in those who went to sleep between 10pm and 10.59pm each night.
Researchers at the University of Exeter looked at data from more than 88,000 British adults between the age of 43 and 74. Participants wore wrist trackers for a week which monitored what time they fell asleep and woke up, and also answered questions about their lifestyles. The team found the lowest rate of heart problems was in those who went to sleep between 10pm and 10.59pm each night
People who went to bed after midnight had a 25 per cent higher chance of developing heart problems.
And getting to bed before 10pm was linked to a 24 per cent higher risk, while rates were 12 per cent higher in those who nodded off between 11pm and midnight.
The research, published in the European Heart Journal, concluded that encouraging people to maintain a regular bedtime could help prevent cases of heart disease at ‘minimal cost’.
Lead author Dr David Plans said: ‘The body has a 24-hour internal clock, called circadian rhythm, that helps regulate physical and mental functioning.
‘The results suggest that early or late bedtimes may be more likely to disrupt the body clock, with adverse consequences for cardiovascular health.’
Dr Plans said: ‘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.
‘The riskiest time was after midnight, potentially because it may reduce the likelihood of seeing morning light, which resets the body clock.’
The study found that the link between bedtime and risk of heart disease was strongest among women, which may be due to hormonal differences and the menopause.
Men who stayed up past midnight did not suffer ill-effects, although those who went to bed before 10pm were more likely to have heart problems.
Dr Plans said: ‘It may be that there is a sex difference in how the endocrine system responds to a disruption in circadian rhythm.
‘Alternatively, the older age of study participants could be a confounding factor since women’s cardiovascular risk increases post-menopause – meaning there may be no difference in the strength of the association between women and men.’ Research shows that decreased oestrogen levels after the menopause increase women’s risk of heart disease.
The study said encouraging people to get to bed before 11pm could reduce the risk of heart disease for millions of people.
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.
‘Sleep timing would be an attractive target for interventions to reduce CVD risk owing to its minimal cost and invasiveness.
‘This intervention could take the form of public health guidance, structured intervention programmes, or technology-based solutions such as smartphone apps.’
Heart and circulatory diseases cause one in four deaths in the UK – around 160,000 deaths each year, and about 7.6 million Britons live with heart disease.
Regina Giblin, Senior Cardiac Nurse at the British Heart Foundation, said: ‘This large study suggests that going to sleep between 10 and 11pm could be the sweet spot for most people to keep their heart healthy long-term.
‘However, it’s important to remember that this study can only show an association and can’t prove cause and effect. More research is needed into sleep timing and duration as a risk factor for heart and circulatory diseases.
‘Getting enough sleep is important for our general wellbeing as well as our heart and circulatory health, and most adults should aim for seven to nine hours of sleep per night.
‘But sleep isn’t the only factor that can impact heart health. It’s also important to look at your lifestyle as knowing your numbers such as blood pressure and cholesterol levels, maintaining a healthy weight and exercising regularly, cutting down on salt and alcohol intake, and eating a balanced diet can also help to keep your heart healthy.’