Those who go to bed before 10pm or after 11pm could be at greater risk of heart disease, a new study suggests.
Research was carried out to identify the link between bed time and heart health, testing 88,000 people to determine results.
The study concluded that the optimum bed time falls between 10pm and 10.59pm, meaning those who head to sleep at this time came out on top in terms of heart health.
Twenty four per cent of participants who went to bed before 10pm were found to have an increased risk of developing heart disease in later life. Those who went to before after midnight saw their risk increase by 25 per cent.
Participants in the study who fell asleep between 11 and 11.59pm had a 12 per cent greater risk.
David Plans from the University of Exeter was one of the researched involved in the study. He said: "The body has a 24-hour internal clock, called circadian rhythm, that helps regulate physical and mental functioning.
"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."
Previously, research suggested that there are links between a sleeping habits and a cardiovascular health.
This study was the first of its kind as it examined the time people went to bed opposed to the duration of time participants slept for.
Participants were recruited over a decade ago as part of a larger research project. The 88,000 people taking part wore a device on their wrists which measures when they went to sleep over a period of seven days.
Five years after launch, researched followed up with participants to find out whether they remained healthy.
It was found that 3,172 participants - 3.6 per cent - had developed some kind of heart disease including heart attacks, strokes, transient ischaemic attacks and heart failure.
Researchers then suggested that those who had gone to sleep between 10pm and 11pm were least at risk of heart problems - even after controlling variables such as age, sex, duration of sleep, smoking status, body mass index, diabetes, blood pressure and socioeconomic status.
Dr Plans added: ""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."
Despite extensive research, the study is not itself enough to prove that later or earlier bedtimes actually cause cardiovascular problems in later life.
Instead, the data shows a correlation between bedtime and heart disease with more research required to examine the direct impacts.
When breaking the data down by sex, the association between heart disease and sleep onset was strongest in women. For men, there was only significant differences for those going to sleep before 10pm.
This could be down to differences in how the hormonal system works in men and women and how it responds to disruption to the body’s internal clock.
The researcher concluded: "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: "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."
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