Several recent studies have shown a relationship between lack of sleep and the occurrence of stroke. In most of these studies, the amount of sleep that predisposes one to stroke is six hours or less. Even though this amount of sleep may seem to be rare and unusual to most of you, several recent surveys have demonstrated that over one-third of the adult population gets six or less hours of sleep per night.
In a series of papers out of the Department of Psychiatry and Sleep Research at Pennsylvania State University, people with insomnia from the surrounding community were studied. Interestingly, they found that insomniacs who sleep less than six hours have a much higher incidence of hypertension and diabetes than those who sleep longer than six hours. Both of these are significant risk factors for the occurrence of stroke.
Why should a lack of sleep result in a higher risk of stroke? The answer seems to lie in an overactive stress system. A shortage of sleep results in many factors that can negatively affect our health. This includes increased metabolic rate, heart rate, and blood pressure, as well as an excessive production of adrenaline and cortisol from the adrenal glands. Most importantly, it results in a state of generalized inflammation. There is a release of inflammatory mediators called cytokines in response to insufficient sleep. These cytokines have several harmful effects. These include damage to the lining and function of our blood vessels, i.e. altering the structure of cholesterol to make it more easily incorporated into atherogenic plaques and increasing the tendency of our platelets to adhere to blood vessel walls and clump, thus increasing the chances of a stroke.
In fact, a study in the journal Sleep titled Short Sleep predicts stroke symptoms in persons of normal weight. In the study, 5,666 people, aged 45 and older, were followed for up to three years. In those who slept less than six hours per night, there was a four times greater risk of stroke than those who slept seven to eight hours.
I believe that what we are learning is that adequate sleep is necessary to insure normal cerebrovascular function. We already knew that inadequate sleep could adversely affect memory, cognition, and mood. However, we are now discovering that the ultimate insult to the brain—stroke–can also be linked to insufficient sleep. Therefore, the take home message is that most of us need seven to nine hours of sleep a night to insure good cerebrovascular health and function. If you are one of those people who chronically gets less than six hours of sleep a night, try to change your habits and get at least seven to nine. If you have tried to do this but still are unable, you are probably suffering from insomnia and should seek professional help.
