Sleep Keeps the Brain Fit

In today's performance-oriented society, sleep is often perceived as a nuisance, as it is the time when one is only unproductive. You can find advice everywhere on how to use your time more efficiently, and this also applies to sleep. There are people who swear by polyphasic sleep and then only take a twenty-minute power nap every three hours instead of really sleeping. The time saved in this way is put into work or self-optimisation. Meanwhile, however, there is growing evidence that sleep is not a bug, but a feature - and we should treat it accordingly.

A new study by a French-British epidemiology team looked at data from 7,959 British civil servants who took part in the Whitehall II study between 1985 and 2016. In it, the civil servants were asked about their sleep habits six times during the duration of the study. Of the subjects who were 50 years old at the start of the study, 521 developed dementia by the end of the study, with an average age of 77.

Brain changes that lead to dementia in the long term (e.g. protein deposits in Alzheimer's disease) begin around 15 to 20 years before the onset of symptoms typical of dementia, such as memory problems. Because the study duration was 25 years, it turned out that a lack of sleep occurring five to ten years before dementia was diagnosed made dementia more likely.

Subjects who reported sleeping six hours or less per night between the ages of 50 and 60 had a 30 per cent increased risk of dementia compared to those who slept seven or more hours. This figure was obtained when socio-demographic factors such as alcohol consumption, smoking, obesity, dietary habits, physical activity ... were taken out of the equation. At first glance, this 30 percent does not sound shockingly high. However, if one now includes all these unhealthy lifestyle habits and factors, the combination of risk factors could be far more than enough to make dementia practically certain in certain cases.

In addition, an American study came to similar conclusions. Here, five hours of sleep or less per night was associated with twice the risk of dementia.

Why is sleep so important?

The question that now arises is why a short duration of sleep promotes the likelihood of dementia. The answer to this is not yet fully understood, but at the moment the most likely reason is that the removal of waste products plays a role. Because the brain needs 20 per cent of the body's total energy, it naturally produces a lot of waste products during the course of the day, such as protein waste, dead cells, etc. These substances are toxic for the nerve cells and must be removed regularly. An example that many people know is when you sleep very little or hardly at all during the night. Then there is a high probability that you will have a headache the next day, for example. The reason for this is that not enough toxins have been removed. What already has an effect after one day can have even greater negative effects in the long term, including a reduction in the ability to think and remember. Only when we get enough sleep is the waste effectively disposed of. In addition, these waste disposal processes in the brain during sleep function less effectively with increasing age. Lack of sleep can therefore set a vicious circle in motion because the already poorly functioning system then has even less time to work.

Sleep well - but how?

We live in a time when good sleep is becoming increasingly rare. One reason is screen time, which is constantly increasing. Basically, good sleep etiquette is important. For example:

You should not look at a screen for at least one hour before going to bed
Do not drink alcohol in the evening
Do not drink alcohol for at least four, but preferably eight hours before going to bed.
Always go to bed at the same time
Make sure the bedroom is well darkened
Relax

If, despite all these measures, you suffer from a persistent sleep disorder, it is important to seek professional or medical advice so that the problem can be clarified and the causes found.