Too much sleep linked with greater risk of stroke

People who regularly sleep for longer than eight hours a day face a higher risk of experiencing a stroke, suggests a recent study co-authored by Warwick University’s Professor Francesco Cappuccio and published in Neurology magazine.

The research followed just under 10,000 people aged between 42 and 81 for 9.5 years.

Participants were asked how long they slept per day, on average, and how well they slept. Adjusting for age, sex, and other relevant factors, sleeping on average over eight hours per day was seen to increase the risk of experiencing a stroke by 46 percent greater than average.

Of the participants, 346 suffered a stroke. The condition is serious, and occurs when blood supply to part of the brain is cut off, either due to a blood clot or when a blood vessel supplying the brain bursts. It is the third most frequent cause of death in the UK, according to the National Health Service.

The risk of stroke was seen to increase greatly in people who increased their sleep duration over the years tested, rather than maintaining an average length.

Risk also doubled for older participants of the study, but the causes of this are not yet clear, and are being pursued through further research.

A correlation between shorter sleeping length and increased risk of stroke was also spotted, but not considered significant enough statistically to draw a link between the two factors.

In order to make their conclusion, the researchers combined their own data with 11 studies into sleep duration and stroke risk drawn from seven different countries. The final number of participants analysed to support Cappuccio’s conclusion was 560,000.