Too much sleep could be linked to heart disease, study finds
When they returned at an average of eight years later, they found 4,381 deaths and 4,365 "major cardiovascular events".
Participants who slept a total of eight to nine hours a day had a 5% greater risk of suffering such an incident than those who slept six to eight hours.
The danger rose to a 17% higher risk for people sleeping between nine and 10 hours a day while those sleeping more than 10 hours a day had a 41% increased risk of cardiovascular disease or death.
The international team wrote in the European Heart Journal: "Sleep is essential to human health, and people spend about a third of their hours sleeping. It is increasingly regarded as an important lifestyle behaviour that can affect cardiovascular disease (CVD) and death."
Co- author Professor Salim Yusuf, from McMaster University, Ontario, Canada, said: "The general public should ensure that they get about six to eight hours of sleep a day.
"On the other hand, if you sleep too much regularly, say more than nine hours a day, then you may want to visit a doctor to check your overall health.