A recent study, published in the online issue of Neurology, the medical journal of the American Academy of Neurology, shows that people who sleep for nine or more hours at night or take long naps during the day time may be at higher risk of stroke.
Further elaborating on the topic, the Chinese scientists have claimed that people who are used to taking a midday nap more than one and half hours were 25% prone to stroke when compared to people who take a regular nap for about 30 minutes. But, people who slept more than nine hours at night and took nap for more than 90 minutes were 85% more likely to have a stroke than people who were moderate sleepers and nappers.
Xiaomin Zhang of Huazhong University of Science and Technology in Wuhan, China, said: "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."
"In addition, long napping and sleeping may suggest an overall inactive lifestyle, which is also related to increased risk of stroke," Zhang added.
31,750 cases were studied
The team of scientists conducted a study that involved 31,750 people in China with an average age of 62. Though none of them had any history of stroke or other major health problems at the beginning of the study, a total of 1,557 stroke cases were reported during the follow-up span lasting for an average of six years.
According to Zhang, midday napping quite common in China. When asked about their sleep and napping habits, 8% of the people admitted of taking naps for more than 90 minutes, while 24% said that they slept nine or more hours at night.
Poor quality of sleep
The study found that those who slept for nine or more hours at night have 23% increased chances of suffering a stroke than people who sleep for seven to less than eight hours at night. The findings were all adjusted for other factors that could affect the risk of stroke, such as diabetes, high blood pressure and smoking.
The researchers also observed that people who had a poor quality of sleep were 29% more likely to later have a stroke than people who said their sleep quality was good.
"These results highlight the importance of moderate napping and sleeping duration and maintaining good sleep quality, especially in middle-age and older adults," Zhang said in his study. He also noted that the study does not prove the cause and effect between long napping and sleeping and stroke. It only shows an association.
Limitations of this study
However, there are several limitations to this study as the information on the sleep habits was collected from questionnaires and it does not include sleep disorders such as snoring and sleep apnea. The actual sleep quantity was not recorded. The paper also indicated that the study involved older and healthy Chinese adults, so the results may not apply to other groups.