What if I sleep 4 hours a day

Little sleep is good for the heart and brain

Almost everyone has heard of statistics and research suggesting that poor sleep increases the risk of cardiovascular and mental disorders, implying that poor sleep is very unhealthy.

However, this approach is wrong: the decisive factor is whether or not someone is fit after five to six hours of sleep. In short sleepers who only need a few hours of rest during the night, there is no evidence of an increased risk of the disease, but certainly in insomnia patients who would like to sleep longer but cannot. This differentiation is very important, said Professor Maurice Ohayon of Stanford University in the USA.

At the conference of the German Society for Sleep Research and Sleep Medicine (DGSM) in Mainz, Ohayon presented the results of a representative analysis of around 16,000 US citizens over the age of 18. For the study, data on sleep behavior were collected, as well as the prevalence of the most important mental and physical illnesses.

Short sleep has a protective effect on the heart

According to this information, almost six percent of those surveyed slept less than six hours a night without suffering from insomnia. In addition to these short sleepers, 8.3 percent of those surveyed had less than six hours of sleep due to an insomnia.

If the sleep doctors around Ohayon looked at the prevalence of important diseases, then there were dramatic differences between the two groups: Compared to people with more than six hours of sleep per night, the rates of heart disease and hypercholesterolemia were around 40 in the short sleepers without insomnia Percent reduced that of high blood pressure by a quarter.

In contrast, insomnics with less than six hours of sleep showed a 24 percent higher rate of hypertension compared to normal sleepers. Musculoskeletal disorders were observed about 64 percent more often, disorders of the blood-forming system occurred even five times more often.

Negative aspects only for insomnia patients

"A short sleep without insomnia seems to be more of a protective factor for cardiovascular disease," concludes Ohayon. In contrast, the expected negative effects were seen in the insomnia patients. There is a connection between lack of sleep, high blood pressure and cardiovascular diseases, especially in insomniacs who have higher blood pressure at night than during the day.

According to data from a Japanese study, the risk of cardiovascular diseases is more than four times higher than that of normal sleepers. With other forms of hypertension, however, this risk does not depend on the length of sleep, explained the expert.

Little sleep is also repeatedly described as a risk factor for obesity. Ohayon and his team were able to confirm this connection in the analysis - for both short sleepers and insomnics: The obesity rate was increased by a fifth to a quarter.

Doesn't "primary insomnia" exist?

In contrast, only the insomnics, but not the short sleepers, showed an increased rate of mental disorders: dysthymia and anxiety disorder were four times more frequently observed in insomnia and sleep duration of less than six hours than in participants with sleep duration of more than six hours.

Depression and post-traumatic stress disorder occurred almost three times as often, and bipolar illness and alcohol addiction were both twice as likely. In contrast, such problems tended to be observed less frequently in short sleepers without insomnia than in normal sleepers: the dysthymia rate was around 80 percent lower, that for depression and bipolar diseases by around 40 percent.

Another difference: Almost half of the insomnia patients reported cognitive problems and fatigue, in the case of the natural short sleepers only about one seventh suffered from such difficulties. A similar differentiation must also be made among the late risers, said the sleep specialist.

There are people who only feel fresh and rested after at least nine hours of sleep, whereas others also sleep nine hours or more, but are still tired. The last variant of the late riser is obviously not that rare.

More than nine hours of sleep a night

In the US analysis, 6.3 percent of respondents said they slept more than nine hours a day. Of these, 38 percent said they spent more than eleven hours in bed on weekends or days off. Of these, in turn, almost 60 percent still did not feel rested after a long sleep.

The less the participants normally slept, the more likely they were to rate an eleven-hour sleep as restful. Only 2.3 percent of those who slept less than six hours during the week - with or without insomnia - felt that eleven hours of sleep on the weekend was not enough.

As a rule, organic and mental illnesses are closely linked to the excessive need for sleep, explained the sleep specialist. More than 60 percent of those affected have an organic condition; According to the data of the analysis, the rate for dysthymia is about twelve times higher, and depression and bipolar diseases are three times more common.

In people with an average of more than ten hours of sleep per night, an organic or psychological underlying disease can almost always be assumed, said the expert. But even in late risers with restful sleep, the US researchers were able to identify a two to three-fold increase in the rate of mental disorders.

So if someone gets along well with less than six hours of sleep, that's a very good sign according to these data. Such people are on average healthier than those who need eight or more hours.

However, such studies say little about cause and effect. It is clear that many organic and mental illnesses affect sleep. Some experts at the conference even suggested saying goodbye to the diagnosis of "primary insomnia". As a rule, the insomnia is always the result of another illness - often an anxiety or arousal disorder.