WUHAN, China — There’s nothing quite as satisfying as hitting the hay after a long day for some much-need shut eye. Similarly, a nice midday nap can be just what the doctor ordered in terms staying fresh and avoiding the afternoon doldrums. However, a new study finds that you may want to make sure you’re not sleeping too much too often. According to researchers from the Huazhong University of Science and Technology in China, regularly taking naps that exceed 90 minutes, or sleeping for over 9 hours each night, may raise one’s chances of suffering a stroke.
Researchers analyzed over 30,000 Chinese citizens, and discovered that those who took regular 90 minute-plus naps were 25% more likely to have a stroke than people who don’t typically nap at all or nap for periods of time under one hour. Additionally, those who usually slept nine or more hours each night were 23% more likely to suffer a stroke than participants sleeping around 6-8 hours per night.
Overall, people who were both long nappers and especially long sleepers were found to be 85% more likely to have a stroke than more moderate sleepers and nappers.
“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, but previous studies have shown that long nappers and sleepers have unfavorable changes in their cholesterol levels and increased waist circumferences, both of which are risk factors for stroke,” says study author Xiaomin Zhang, MD, PhD, in a release. “In addition, long napping and sleeping may suggest an overall inactive lifestyle, which is also related to increased risk of stroke.”
In total, 31,750 people with an average age of 62 took part in the research. Each participant was followed for an average of six years. While none of the study participants had any history of prior strokes or heart problems at the beginning of the observation period, 1,557 strokes occurred over the course of the study.
Each participant was also asked about their personal sleep habits, with 8% saying they usually take naps longer than 90 minutes and 24% saying they typically sleep for nine or more hours each night. It’s worth mentioning that midday naps are much more common in China than in many other parts of the world.
The research team were sure to account for other factors that may influence stroke risk, such as smoking habits, diabetes, or high blood pressure.
Participants were also asked about their sleep quality; those who reported poor sleep quality were 29% more at risk of a stroke than those who reported higher quality sleep.
“These results highlight the importance of moderate napping and sleeping duration and maintaining good sleep quality, especially in middle-age and older adults,” Dr. Zhang adds.
Dr. Zhang also made it a point to emphasize that this research does not validate a cause and effect relationship between sleep duration and stroke occurrence, but, it does illustrate an association. Furthermore, this set of research focused solely on older adults, so it is not a given that the same findings would hold true regarding younger people.
The study is published in the scientific journal Neurology.