What are sleep disorders?
On average, we sleep about a third of our lives. That means that we will sleep for about 30 years in total. The human sleep-wake cycle is divided over 24 hours, this is called the circadian rhythm.
If we were to remove all the elements that could indicate time (light, watches, radio, etc.) from our environment, we would still sleep and wake according to the circadian rhythm. But due to a lack of light, a shift in melatonin production will shift this rhythm every day to a slightly later time.
Our biological clock is regulated by nuclei in the hypothalamus. Light is the most important element in the environment that helps regulate our sleep-wake rhythm through retinohypothalamic connections.
Not only the sleep-wake rhythm but also cardiovascular processes, respiratory processes, hormonal processes, attention regulation, etc. follow the circadian rhythm.
Our sleep consists of REM sleep (Rapid Eye Movements) and Non-REM sleep. Normally there are 4 to 5 sleep phases, each lasting 90 to 120 minutes. Mainly areas in the brainstem will regulate these cycles. The correct mechanism of action of sleep is still not fully known.
When sleep is not so evident.
More than 100 different types of sleep disorders have been described. Most of the time it is about insufficient qualitative sleep, interrupted sleep, not being able to sleep (insomnia), but also extreme sleepiness (hypersomnia), respiratory disorders (snoring, apnea), disorders caused by involuntary movements, sleep paralysis, sleep disorders due to substance abuse (alcohol, coffee, medication).
Sleep disorders are divided into two main categories: primary and secondary sleep disorders.
Primary sleep disorders:
These forms are not the result of an underlying condition or substance abuse.
Psychogenic insomnia: this form occurs mainly in stress. Sleeping in and / or sleeping through is made more difficult because the patient cannot relax.
Pseudo-insomnia: feeling that one sleeps badly. However, objective tests and measurements in a specialized sleep center show normal sleep cycles.
Restless legs syndrome: As the name suggests, one experiences tingling or jitters (ants) in the legs when they are at rest (in bed, while watching TV or reading a book, etc.).
Periodic leg movements: during sleep, the legs make violent, shocking movements. This can take a few minutes to a few hours. Often this goes together with restless legs syndrome but it can also occur in isolation. Sleeping is disrupted by the sudden, uncontrollable movements of the legs.
Sometimes both, the restless legs syndrome and the periodic leg movements, can be a secondary sleep disorder e.g. with uremia, iron deficiency or by using medicines.
Secondary sleep disorders:
These forms are the result of an underlying condition or substance abuse.
Known examples are dementia, depression, Parkinson's disease, dystonia, epilepsy, headache, fibromyalgia, chronic fatigue syndrome, burn-out syndrome, etc.
Disorders of the circadian rhythm: this occurs in people who work in shifts (with night shifts). The known jet lag is also a typical example of a disrupted circadian rhythm.
How can sleep disorders be treated?
When there is a sleep disorder, it is important that this is properly examined by specialized people in a sleep center.
Medicinal support can be useful to promote sleep, and sleep and cognitive behavioral therapy has already proven its worth.
Neuromodulation such as tES or neurofeedback can be also be incorporated to existing therapies.
When it comes to a secondary sleep disorder, it is advisable to treat the underlying problem. Here, too, neuromodulation can play an important role.