Too Much Sleep Means Higher Stroke Risk?

People who sleep too much, that is, more than 8 hours a day, have a higher risk of stroke, according to a new study.

Previous research has suggested a link between sleep and risk of stroke, however, the underlying mechanism still remains a mystery. Now this new study indicates that this association exists regardless of normal risk factors for cardiovascular disease.

Described in the journal Neurology, a team at the University of Cambridge studied approximately 10,000 people aged 42-81 from the European Prospective Investigation into Cancer (EPIC)-Norfolk. For roughly the next 10 years, they questioned participants about how many hours they slept on average as well as their quality of sleep. Almost seven out of 10 participants reportedly slept between 6 and 8 hours a day, whereas one in 10 slept for over 8 hours a day.

Those who slept for less than 6 hours or more than 8 hours were typically older, women, and less active.

During the course of the study, 634 participants suffered from a stroke, either non-fatal or fatal. The researchers found that those who slept for more than 8 hours a day had a 46 percent increased risk of stroke than average. Meanwhile, people who slept less than 6 hours a day only had an 18 percent increased risk.

A follow-up determined that people who consistently slept longer actually doubled their risk of stroke, compared to those who persistently slept between 6 and 8 hours. Astonishingly, the risk was even worse for those who reportedly increased their sleep from short to long - four times that of people who maintained an average sleep duration.

"We need to understand the reasons behind the link between sleep and stroke risk. What is happening in the body that causes this link? With further research, we may find that excessive sleep proves to be an early indicator of increased stroke risk, particularly among older people," Kay-Tee Khaw, senior author on the study, said in a statement.

It's likely that with less work and fewer social demands, older people tend to sleep more with nothing better to do. And while sleep is hardly ever seen as a bad thing, even a good thing necessary to maintain a healthy life, researchers speculate that too much sleep could disrupt the body's metabolism and raise levels of the stress hormone cortisol, both of which may lead to higher blood pressure and increased stroke risk.

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