A global study published by the European Heart Journal says that sleeping more than the recommended six to eight hours a night for adults is associated with increases in death and cardiovascular diseases.
The global study looked at data from 21 countries and across seven regions and revealed that people who slept more than the recommended maximum limit of eight hours had a rise in major cardiovascular events such as strokes or heart failure and with up to a 41% increase in death. However, authors of the study say that underlying conditions may be causing individuals to sleep longer which could then increase the risks of cardiovascular disease and death.
A rising risk among daytime nappers, who had more than six hours of nighttime sleep was discovered by Chuangshi Wang, a Ph.D. student at McMaster and Peking Union Medical College in China. But in individuals sleeping less than six hours “a daytime nap seemed to compensate for the lack of sleep at night and to mitigate the risks,” Wang explained.
This study in China adds to ones which have been done in North America, Europe and Japan now giving it a global view. However, “Even though the findings were very interesting they don’t prove cause and effect,” said Julie Ward, a senior cardiac nurse at the British Heart Foundation, who was not involved in the study.
In 2014, the Center For Disease and Prevention Control (CDC) studied the sleeping habits of 126,632 adults between the age of 35 and 70 from 21 countries who reported not getting enough sleep. Then over an average of 7.8 years they were followed up.
What they found was that for those who under-slept the statistics were not significant, and the greatest risk to an increase in cardiovascular disease was instead seen among those who overslept beyond the max of 8 hours.
According to the study, “For those sleeping eight to nine hours, 8.4 per 1,000 people developed cardiovascular disease or died each year. This rose even further in those sleeping nine to 10 hours (10.4 per 1,000) and again among those sleeping more than 10 hours (14.8 per 1,000). This equates to an increase in risk of a 5%, 17% and 41%, respectively, compared with people who slept the recommended amount of hours.”
But Wang and Cappuccino both believe that underlying causes may be the culprit: ”it’s not that long sleep causes death or ill health but that ill health will cause you to sleep more.” For instance, a person who has cancer may be more tired and debilitated thus causing them to sleep more.
Wang explained that the optimal duration of sleep of six to eight hours per night for optimum health is the main takeaway from the study and that doctors should include asking their patients about their sleep habits which could enlighten them to the possibilities of underlying causes to ill health in their patients.