TORONTO -- Taking long naps and sleeping for longer than nine hours a night could increase your risk of a stroke, a new study suggests.

According to the study, people who took midday naps longer than 90 minutes were 25 per cent more likely to have a stroke later on in life, compared to those who only took naps of half an hour or shorter.

It found these long nappers and long sleepers were 85 per cent more likely to later have a stroke than moderate nappers and sleepers who slept 7 to 8 hours.

The Chinese scientists, who published their findings in the journal Neurology, also found that people who said their sleep quality was poor were 29 per cent more likely to suffer a stroke than restful sleepers.

"These results highlight the importance of moderate napping and sleeping duration and maintaining good sleep quality, especially in middle-age and older adults," study author Xiaomin Zhang of Huazhong University of Science and Technology said in a statement.

The study doesn’t prove that long sleeping and napping lead to strokes, just that they’re potentially linked. The authors were also cautious about exactly what the results meant.

“More research is needed to understand how taking long naps and sleeping longer hours at night may be tied to an increased risk of stroke,” Zhang said.

He suggested that “long napping and sleeping may suggest an overall inactive lifestyle, which is also related to increased risk of stroke.”

Zhang also cited previous studies that found nappers and sleepers have “unfavorable changes” to their waist sizes and cholesterol levels -- both of which linked to an increased risk of a stroke.

In addition to the other findings, researchers also determined people who took naps lasting 31 minutes to an hour were no more likely to have a stroke compared to people who took naps shorter than 30 minutes.


Zhang’s team examined 31,750 people in China who had an average age of 62, none of whom had a history of stroke at the start of the study. On average, people were followed for six years and asked about their sleep and napping habits through questionnaires.

During that time, there were 1,557 cases of stroke. The results were adjusted for other factors that could affect the risk of stroke, including high blood pressure, diabetes and smoking.

Some limitations of the study included that the data was all self-reported in the questionnaires. Therefore, information such as exactly how long the subjects slept and other sleep disorders wasn’t collected.

Another drawback is that the participants were mainly older, healthy adults.