Getting a good night’s sleep isn’t just good for having a productive tomorrow — sufficient sleep is also important for your physical and mental health.
According to the CDC, not getting enough sleep could be a risk factor for things like heart disease and high blood pressure, and most adults should be getting at least 7 hours every night. But now, a new study suggests that when you go to bed could be a factor in your health as well, NBC News reports. Researchers with Huma Therapeutics, a British medical tech company, looked at whether someone’s bedtime correlated with their risk of developing heart disease. They published their results this month in European Heart Journal – Digital Health.
The data was gathered from a massive survey known as the UK Biobank, so they could look at data from over 80,000 people. Participants wore activity monitors on their wrists for a week, and so the researchers could determine when they went to sleep. They then cross-referenced that data with participants’ known instances of heart issues like stroke and heart failure in the years after that sleep analysis, though they didn’t look at any fatal events.
People were divided into four groups — whether they fell asleep before 10 PM, between 10 and 11 PM, between 11 PM and midnight, or after midnight. After adjusting for sleep duration and quality, as well as some preexisting risks for cardiovascular disease, people who went to bed between 10 and 11 had a lower rate of heart disease than the other three bedtime groups.
In the fully adjusted model, going to bed between 11 and midnight was associated with about a 12% increase in heart disease compared to bedtimes between 10 and 11 PM. Going to bed both before 10 PM and after midnight was associated with about a 24-25% increase in heart disease when compared to bedtimes between 10 and 11. These are all relatively small increases in risk, however, all were considered statistically significant.
Interestingly, these results didn’t seem to be the same for men and women. For men, only going to bed before 10 PM correlated with a 17% increased risk of heart disease compared to bedtimes between 10 and 11. Going to bed any time after 11 made no significant difference compared to the 10-11 cohort.
But for women, going to bed before 10 PM was associated with a 34% increased risk of heart disease, and going to bed after midnight came with a 63% increased risk when compared to the 10-11 PM group. Going to bed between 11-12 PM wasn’t significantly different from the 10-11 PM group in women.
These results would seem to suggest that somewhere between 10 and 11 PM is an optimal bedtime for adults. But the authors are careful to note that this study does “not show causality,” meaning that bedtimes aren’t necessarily the cause of changing heart disease risk, just correlated with it. They also noted that their study group was mostly white, and often more well-off economically, limiting the potential universality of these findings.
The most important thing you can do regarding your sleep is get enough quality time sawing those logs. The CDC recommends making your bedroom a quiet, comfortable space without screens, getting exercise during the day, and limiting late-day caffeine. Notably, they also recommend choosing a bedtime and sticking with it, whatever it might be.
And these rules don’t just apply to adults — kids need even more sleep than their parents, the CDC says, with a recommended 12-16 hours for babies 4-12 months old to a full 8-10 hours for teenagers.