Dementia sufferers have insomnia

From: Alzheimer Info 4/17

Why do people have to sleep? To this day, science has not been able to give a clear answer to this question. One thing is clear: we cannot live without sleep. Sleep and memory are linked in different ways. While we sleep, information in our brain is sorted, transferred to long-term memory or deleted. Those who sleep badly over the long term have, among other things, a lower mental performance.

The need for sleep varies from person to person and is very genetically determined. This applies both to the time at which we like to go to sleep and to the duration of sleep. People can adapt to a certain extent, for example getting up early, sleeping less or working at night. But it is probably not healthy to live against your internal clock for a long period of time.

The sleep-wake rhythm is controlled by hormones and so-called transmitter substances in the brain. The most important hormone is melatonin, which makes you tired and is only released in the dark. Another important substance is adenosine, which is produced through physical activity. That is why light and darkness or movement play an important role in dealing with sleep disorders.

Sleep in old age

Older people sleep shorter, less deeply and wake up more often. The entire sleep-wake cycle can change with age. This is also due to the fact that older people react less strongly to external timers such as light and darkness. For many people, sleep disorders are part of getting older. There is a close and reciprocal relationship between dementia and sleep: poor sleep promotes the occurrence of dementia, and dementia leads to poor sleep.

Sleep disorders increase the risk of dementia

Scientific studies have shown that sleep disorders in healthy adults are linked to an increased risk of dementia. A common form of sleep disorder is sleep apnea, usually a result of being overweight or changes in the nasopharynx. In this syndrome, the upper windpipe closes briefly during sleep and a feeling of suffocation occurs. As a result, night sleep is less deep and restful. Breathing disorders during the night are associated with a 2 to 6-fold increased risk of cognitive impairment and dementia.

Sleep disorders and Alzheimer's dementia

It can be assumed that sleep disorders are closely related to the deposition of beta-amyloid in the brain. These deposits are one of the causes of Alzheimer's disease. It is known, for example, that sleep deprivation causes increased excitability of nerve cells, which is associated with increased deposition of beta-amyloid. But most of all, sleep seems to be important to the drainage system in the brain. This drainage system removes harmful metabolic products that arise in neurodegenerative diseases (e.g. beta-amyloid). The drainage system is particularly active when we are asleep and poor sleep inhibits the system.

Dementia leads to insomnia

Sleep disorders apparently favor dementia. At the same time, people with dementia very often suffer from sleep disorders that go beyond what is common in old age. Sleep apnea, for example, is observed in up to 80 percent of people with dementia, and the frequency increases with the severity of the dementia. Typical is also a disturbed sleep-wake rhythm, frequent nodding off during the day and restlessness and behavior disorders in the evening (so-called "sundowning").

These aspects of dementia are often a major burden, especially for family carers. They shape the daily routine and disturb the night's sleep. This means that relatives themselves sleep worse, are less productive and satisfied. However, there are ways to promote healthy sleep, the most important of which are addressed in this issue. Using these opportunities is worthwhile for everyone involved.

Astrid noise
German Alzheimer's Society, Berlin
Prof. Dr. Alexander Kurz
Klinikum rechts der Isar, Munich

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