Duration of sleep: when does it become dangerous for your health?

How many hours a person should sleep per day is difficult to say, because the need for sleep is very individual. However, there are some points that can be generalized. French and British researchers have further investigated the extent to which the duration of sleep influences the onset of one or more chronic diseases and overall mortality.

The baseline: As people age, it is common for them to suffer from chronic diseases such as diabetes, osteoarthritis or dementia. If several such diseases occur at the same time, it is called multimorbidity. The researchers of the current study wanted to find out how the duration of sleep influences the development of multimorbidity and mortality in the elderly.

For this purpose, the data of more than 7,000 British women and men were evaluated. In the period from 1985 to 2016, the 50 to 70-year-olds had themselves tracked their sleep duration. The average sleep duration at the ages of 50, 60 and 70 years was determined from the data and related to newly emerging chronic diseases.

Conditions observed include: diabetes, cancer, coronary artery disease, stroke, heart failure, chronic lung disease, liver disease, kidney disease, arthritis and rheumatism, Parkinson’s disease, depression, dementia and other mental illnesses.

The evaluation of sleep duration showed that most subjects went to sleep for about seven hours, followed by six and eight hours a night. Some participants also slept significantly less, lasting five hours or less. The 50 to 70 year olds slept the least more than nine hours a night.

In the study, the researchers spoke of multimorbidity if two or more of the above-mentioned chronic diseases had developed in the subjects during the 25-year observation period.

The result of the evaluation: A short sleep of five hours or less per night is associated with a 20 percent higher risk of developing a chronic disease compared to a sleep of seven hours. The chance of developing further diseases after the first also increases by 20 percent. There is thus a clear link between sleep deprivation and multimorbidity.

However, it could not be established that premature death is also promoted by a short sleep duration. Similarly, a very long sleep duration of nine or more hours per night did not lead to an increased risk of chronic disease.

The authors themselves considered that one of the weak points of the study was that the number of ‘sleepers’ (longer than nine hours a night) was quite small. The conclusion for this group is therefore less meaningful. Further research into the relationship between very long sleep duration and the development of chronic diseases is therefore necessary.

The authors also point out that self-determination of how long the test taker slept can also lead to potential errors. In addition, most subjects were white Europeans, so the results cannot be generalized without limitations.

Source: