People who regularly go to bed between 10pm and 11pm are less likely to develop heart or circulatory diseases, a study has shown.
Researchers found that people who regularly went to sleep later or earlier than this “ideal” window were more likely to develop cardiovascular disease, even when sleep duration or sleep irregularity were taken into consideration.
The research, published in the European Heart Journal – Digital Health, involved looking at the sleep onset and waking up times of more than 88,026 people, collected from wearable devices over a period of seven days.
After an average follow-up period of almost six years, a total of 3,172 cases of cardiovascular disease (CVD) were reported (3.6% of participants). Most of these involved people who fell asleep outside of the 10pm to 11pm window.
People who fell asleep after midnight had a 25% higher risk of developing heart or circulatory disease. Those who fell asleep between 11:00 and 11:59pm had a 12% higher risk, while those who fell asleep before 10pm saw their risk increase by 24%.
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The association between sleep onset time and increased risk of cardiovascular disease was stronger in females, but men only saw their risk increase when they fell asleep before 10pm.
Dr David Plans from the University of Exeter said: “The body has a 24-hour internal clock, called circadian rhythm, that helps regulate physical and mental functioning.
“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.
“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.”
The study recommends further research into sleep timing as a cardiac risk factor, particularly for women.
“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,” the study concludes.
Regina Giblin, a senior cardiac nurse at the British Heart Foundation, said: “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.”
