Could Too Much Sleep Increase Stroke Risk?

Getting enough sleep is important for optimal health but it turns out that too much of a good thing might not be all that good after all.  A new study advises that sleeping more than 9 hours a night, or taking extended midday naps, could increase risk for incident of stroke.

A large, prospective cohort study says that 9 hours of sleep—when compared against 7 or 8 hours—could increase stroke risk by as much as 23 percent.  Alternately, the research advise that 6 hours of sleep did not appear to have any significant risk on stroke incident.  

In addition to this, the researcher say that a midday nap lasting at least 90 minutes (and likely longer) might also be associated with 25 percent higher stroke risk (when compared with naps of up to 30 minutes).

For the study, the researchers analyzed data collected from 31,750 retired employees (all with the Dongfeng Motor Corporation, in China). All of these people had an average baseline age of 62; the study followed this cohort for, on average, of 6.2 years.  It is important to note that those involved with this study had no history of coronary heart disease, stroke, or cancer.  By answering a simple questionnaire, the researchers outlined their typical sleeping and napping habits/patterns, and rated their characteristic sleep quality. 

In all, nearly 24 percent reported sleeping at least 9 hours; more than 7 percent reported midday naps longer than 90 minutes. 

Over the follow-up period, 1,557 incident stroke cases were reported, most of which were ischemic.  Compared against those who reported good sleep quality, the poor quality sleepers showed a 29 percent higher risk of total stroke. 

Huazhong University of Science and Technology’s Dr. Xiamin Zhang, MD, PhD, comments that this data is still preliminary, but quite revealing. Dr. Zhang notes, “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.”

The study author goes on to say, “But previous studies have shown that long nappers and sleepers have unfavourable 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 of stroke.”

It should also be noted, however, that the research did not prove that sleeping more is directly related to higher stroke risk.