For this retrospective study, researchers looked at data collected in the U.S. National Health and Nutrition Examination Survey, which tracked responses from over 14,000 people for a median of 7.5 years. Those surveyed were 46 years old on average, half were women, and 53% were not white.
Researchers were specifically looking for how much sleep the participants were getting, as well as their atherosclerotic cardiovascular disease (ASCVD) risk scores, and their levels of C-reactive protein (CRP), an inflammatory marker linked with heart disease.
Interestingly, they noticed there seemed to be a sweet spot of sleep length that was associated with a low ASCVD risk score (a higher score can indicate greater likeliness of heart attack or stroke): Those who slept six to seven hours a night actually had the lowest chance of dying from a heart attack or stroke, compared to those who got less or more sleep. (Yep, too much sleep can be problematic too.)
Based on the findings, the research suggests getting six to seven hours of sleep offers the lowest risk to your heart. As lead author of the study, Kartik Gupta, M.D., notes in a news release, “Participants who slept less than six hours or more than seven hours had a higher chance of death due to cardiac causes.”
The ASCVD risk score wasn’t greater if participants got more than seven hours, but the levels of CRP were. More research will be necessary to further confirm the findings.
You’ll note that this six- to seven-hour window doesn’t match up with the seven to nine hours recommended by the National Sleep Foundation: A good reminder that there is no universally agreed-upon amount of time we should all be spending in bed.
As many experts have told mbg, everyone’s sleep needs are a little different. In addition to aiming for a certain number of hours in bed every night, it’s also important to consider how you feel when you wake up in the morning to assess your overall sleep quality.
“Just because you are lying in bed for seven hours doesn’t mean that you are getting good-quality sleep,” Gupta reiterates.