We all know sleep deprivation is bad for our health, increasing our risk of heart disease and stroke, not to mention making us hella cranky. 

But a new study has found sleeping for longer than the recommended six to eight hours per night can also have negative health outcomes – and even early death. 

[Read More: What happens to you brain and body when you only get six hours sleep]

The study of more than 116,000 people in seven regions of the world looked at cases of heart disease, stroke and death over a period of eight years, compared to the reported sleeping times. 

People who slept a total of eight to nine hours per night had a five per cent increased risk of these negative outcomes, compared to those who slept for the recommended six to eight hours. 

And duvet lovers will be disappointed to know the more you sleep, the more the risk increases. 

People sleeping between nine and 10 hours a night had an increased risk of 17 per cent and those sleeping more than 10 hours a day had a 41 per cent increased risk. The researchers also found a nine per cent increased risk for people who slept six hours or fewer. 

Lead author of the publication, Chuangshi Wang, a PhD student at McMaster and Peking Union Medical College, Chinese Academy of Medical Sciences, said that given that this is an observational study, it only shows an association rather than proving a causal relationship, “We cannot say that too much sleep per se causes cardiovascular diseases,” he said. 

“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.”

Professor Salim Yusuf, the principal investigator of the study, advised people who regularly sleep for more than nine hours a day to visit a doctor to check their overall health.