Too much and too little sleep harms health

Mature man waking up for routine daily job

Sleeping too much is just as harmful as too little sleep, especially when it comes to raising the risk of cardiovascular problems and premature death, says a new study.

The Centers for Disease Control and Prevention (CDC) in the US had earlier issued warnings that sleep deprivation raises the risk of various chronic conditions such as diabetes, cardiovascular disease, obesity, and depression.

Now, researchers at the McMaster University in Canada and Peking Union Medical College in China say that sleeping too much could also affect health in a similar manner. For their study, the researchers examined the sleeping habits of more than 116,000 people aged between 35 and 70 years. The study also included information about the participants’ socioeconomic status, lifestyle habits, physical activity, diet, use of various medications, and family history of chronic conditions.

Overall, 4,381 people died and 4,365 people had a heart attack or stroke during the 8-year follow-up period of the study. The study revealed that people who regularly slept more than the recommended 6–8 hours a night were more likely to die prematurely or develop cardiovascular disease.

More specifically, the risk of premature death or cardiovascular conditions was 5 percent higher for people who slept 8–9 hours than for people who slept the recommended amount.

Those who slept 9–10 hours were 17 percent more likely to die or develop heart and blood vessel conditions. Similarly, people who regularly slept more than 10 hours were 41 percent more likely to die prematurely or develop cardiovascular problems. The study also found a 9 percent higher risk of similar outcomes among those who slept 6 hours or less. However, the authors caution that this increase was not statistically significant.

Given the observational nature of the study which only shows an association rather than any causal relationship, the team said they could not categorically state that too much sleep per se causes cardiovascular diseases. However, too little sleep could be an underlying contributor to death and cases of cardiovascular disease, and too much sleep may indicate underlying conditions that increase risk, they said.

The researchers recommended that doctors should include questions about the duration of sleep and daytime naps in their clinical histories of patients as it could be helpful in identifying people at high risk of heart and blood vessel problems or death.