A new study, published in European Heart Journal, has found that going to bed between 10:00 and 11:00 pm is associated with a lower risk of developing heart disease, according to Science Daily.

Study author Dr. David Plans of the University of Exeter, UK, 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.”

The study looked at more than 88,000 individuals in the UK Biobank recruited from 2006 to 2010. The researchers found that during an average follow-up of 5.7 years, more than 3,170 participants developed cardiovascular disease and the incidence was highest among those who slept at midnight or later, while it was the lowest in those with sleep onset from 10:00 to 10:59 pm.

The team explained that there was a 25% higher risk of cardiovascular disease with sleep onset at midnight or later.

Furthermore, the association between late bedtime and increased cardiovascular risk was stronger in women.

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.”

However, Dr. Plans noted that it is unclear why there was a stronger association between sleep onset and cardiovascular disease in women.

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

Dr. Plans added. “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,” he added.