Is It Dangerous to Oversleep?


The effects of undersleeping are well-known. Those with insomnia often suffer physical side effects, ranging from mental to physical conditions. Sleep deprivation has been linked to several chronic diseases, including obesity, depression, and heart disease.

However, did you know that oversleeping can also negatively impact your health? New data suggests that oversleeping can be just as detrimental as undersleeping. 

The Research on Oversleeping

Chuangshi Wang, a doctoral candidate at McMaster University in Ontario in, Canada, and Peking Union Medical College at the Chinese Academy of Medical Sciences set out to study the effects of oversleeping. For the study, they examined over 116,000 people between the ages of 35 and 70. 

The researchers were looking critically at the participant’s sleep habits. The researchers also gathered background knowledge on each participant’s medical history, current conditions, socioeconomic status, diet, exercise regimen, medication use, and more.

The study was conducted for eight years, tracking sleep duration patterns and quality. During those eight years, over 4,000 participants died. Another 4,365 people suffered a stroke or heart attack during the study. 

Wang analyzed the sleeping habits of those who died or had major cardiovascular events during this period. What was found is that those who regularly slept more than 8 hours per day were at a higher risk of cardiovascular disease or premature death. 

For those who regularly slept 8-9 hours, the risk of premature death or cardiovascular events was 5% higher than those who slept the recommended amount each night.

Shockingly, those who regularly slept ten or more hours were 41% more likely to experience premature death or cardiovascular disease.

However, this is an observational study. One cannot directly correlate oversleeping and having a heart attack just from this data. Each participant was unique and had preexisting conditions. 

Oversleeping could have been a symptom of underlying and undiagnosed cardiovascular trouble. Or oversleeping could really be a risk factor in suffering major cardiovascular events and premature death.

The bottom line is that this observational study presents exciting data but isn’t conclusive enough to draw a direct correlation. The main takeaway from the study is that the optimal and healthy range for adults to be sleeping each night is 6-8 hours. Anything above or below carries different potential risks. 


This observational study on sleep duration presents some interesting new data. Essentially, the study found adverse health effects for those who underslept and overslept. The data showed that the risk of cardiovascular disease and premature death was much higher for those who regularly overslept.

Though this study is purely observational, it suggests that oversleeping may not be harmless. As such, it’s best to get the recommended 6-8 hours of sleep per night and monitor your sleep schedule to ensure you get enough shut-eye (but not too much) for optimal health.