Most people are aware that getting plenty of rest is essential to staying healthy, and experts recommend that adults get seven to nine hours of sleep every night. However, the importance of precise bedtimes remains relatively unexplored, and new research from the University of Exeter is attempting to change this.
A study led by researcher Dr. David Plans has concluded that the risk of heart disease is greatly decreased by going to sleep between 10 and 11 pm. Dr. Plans noted that this bedtime range is very specific, with heart-related problems increasing for both later and earlier bedtimes.
“The body has a 24-hour internal clock, called circadian rhythm, that helps regulate physical and mental functioning,” explained Dr. Plans. “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.”
Based on data in the UK Biobank, the study objectively measured the bedtimes of over 88,000 adults with an average age of 61 years. The sleep onset data was collected through wrist-worn smart devices. Participants also completed questionnaires to provide information on their demographic, lifestyle, and physical condition.
The individuals were followed for an average of 5.7 years. During this time frame, 3,172 participants were diagnosed with cardiovascular disease. The lowest risk was found among those who had bedtimes between 10 and 11 pm, while the highest risk was found among individuals who fell asleep at midnight or later.
“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” stated Dr. Plans. “The riskiest time was after midnight, potentially because it may reduce the likelihood of seeing morning light, which resets the body clock.”
Although late bedtimes were significant, the analysis revealed that there was a 24 percent increase in cardiovascular risk among those who typically fell asleep before 10 pm. The association was strongest among women, who appeared to be affected by both early and late sleep schedules, while heart-related issues in men were only linked with bedtimes before 10 pm.
It is currently unclear as to why there is a stronger association between cardiovascular disease and sleep onset in women. Plans hypothesized that “it may be that there is a sex difference in how the endocrine system responds to a disruption in circadian rhythm.”
He continued to suggest an alternative conclusion, that 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.
The research is published in European Heart Journal – Digital Health.
By Calum Vaughan, Earth.com Staff Writer