Good sleeping patterns and habits improve one’s overall health. That’s why we’re trying to do a better job of tracking our sleep. We want to determine how to improve the experience while simultaneously connecting that sleep data to other health parameters that wearable devices monitor. While we’re in the early days of more sophisticated sleep tracking, we already have plenty of studies that have used technology to measure sleep and determine connections to health issues. The newest study was shared on Tuesday. A team of researchers determined a particular time of day when we should go to sleep. An earlier or later bedtime might increase the risk of heart disease. There is a caveat in all of this. The researchers can’t prove that going to bed at the wrong time will necessarily lead to cardiovascular illness.
The perfect time to go to sleep
Researchers found that people who go to sleep between 10:00 and 10:59 p.m. have a lower risk of developing heart disease than those who chose earlier or later bedtimes. Published in the European Heart Journal – Digital Health, the study shows that people who go to sleep between 11:00 and 11:59 p.m. are 12% more likely to develop heart disease. Those with a bedtime past midnight have a 25% higher risk of cardiovascular disease. Sleeping before 10:00 p.m. is almost as dangerous, with the study indicating a 24% higher risk of heart issues.
Notably, the scientists could not prove that sleep onset time will lead to a higher risk of heart disease. There are undoubtedly other factors that increase the risk aside from one’s bedtime.
“The body has a 24-hour internal clock, called circadian rhythm, that helps regulate physical and mental functioning,” study author Dr. David Plans said in a statement. “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.”
How researchers linked sleep time to heart disease
The study included 88,026 individuals that UK Biobank recruited between 2006 and 2010. The average age was 61, with 58% of them being women. Participants wore an accelerometer on the wrist for seven days. That’s how the authors determined the sleep onset and waking up times. On top of that, the volunteers also completed demographic, lifestyle, health, and physical assessments and questionnaires.
The researchers defined the following conditions as new cardiovascular diseases in volunteers: heart attack, heart failure, chronic ischemic heart disease, stroke, and transient ischemic attack. They followed up with the volunteers an average of 5.7 years later. Some 3,172 participants had developed one of these heart conditions.
The authors also adjusted for age, sex, sleep duration, sleep irregularity, smoking habits, body max index, diabetes, blood pressure, cholesterol levels, socioeconomic status. They looked at whether people were self-defined as early birds or night owls. The conclusion was the same. People with a bedtime between 10:00 and 10:59 p.m. have a lower risk of developing heart disease.
Should you change your bedtime?
When analyzing men and women, the authors found a few striking differences. The association with increased heart disease was stronger in women who went to sleep late or early.
Sleep onset before 10:00 p.m. remained a significant risk for men. The researchers can’t explain why the association between sleep time and heart issues is stronger in women. Plans noted that the older age of the study participants might be a factor. Women have an increased risk of heart disease after menopause.
“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,” Plans concluded. “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 researchers say the study also demonstrates “the potential utility of collecting information about sleep parameters via accelerometry-capable wearable devices, which may serve as novel cardiovascular risk indicators.”