Normal sleep. Normal sleep and insomnia

Normal sleep is characterized by a certain electrical activity, which can be recorded on the EEG. Based on these data, sleep is divided into five stages. Sleep stages 1-4 are characterized by slow eye movements (NREM sleep), and sleep stage 5 is the period of rapid eye movement (REM sleep): 

• Stage 1 is 5% sleep; it is a shallow dream;
• Stage 2 accounts for 45% of sleep and is characterized on the EEG by the “spindle of sleep” waves;
• Stage 3 and 4 are the deepest stages of sleep, comprising 12 and 13% of sleep, respectively. These stages are often classified together as slow-wave sleep, or 8-rhythms;
• Stage 5 is 25% sleep; on the EEG is reflected by low-voltage desynchronized gear waves.

The time between the onset of sleep and the initiation of the first part of REM sleep is called latent REM-chom (usually 90 minutes). NREM is a calm state with low blood pressure and a cardiac and respiratory rate. During these stages, restless movements occur, and dreams are clear and meaningful. During REM sleep, muscle tone is reduced and the subject is motionless. However, blood pressure, cardiac and respiratory functions are increased, there is a partial or complete erection, dreams are abstract and unreal. 

Central control of sleep is a complex process that involves: • serononergic neurons in the suture nuclei; • noradrenergic neurons of a bluish spot; • AH-containing neurons within the nucleus of the warolium suture, which play a central role in the production of REM sleep. 

The bioelectric activity of sleep fluctuations can be controlled by melatonin, which accumulates in the pineal gland, which in turn is controlled by the hypothalamus. It is likely that the on-off sleep switch is located in the hypothalamus as part of the neuronal circuit connecting the hypothalamus to the reticular activating system. 

The normal duration of sleep for adults is 6-9 hours. The absence of REM sleep leads to irritability, lethargy and subsequent ricochet in REM sleep. Prolonged complete sleep deprivation can be fatal. 

A variety of sleep disorders was noted in the study of mental illness: • with depression there is a noticeable decrease in latent REM sleep and an increase in REM sleep; • Alzheimer’s disease leads to a decrease in latent REM sleep and slow wave sleep. 

Various drugs alter the bioelectric activity of sleep : • benzodiazepines and, to a lesser extent, antidepressants reduce REM sleep; • drugs that increase the release of dopamine (for example, amphetamine) also increase the wakefulness period. 

Insomnia is a common and vague sleep disorder that can be detected in 40-50% of people. Of these cases: • 30-35% – insomnia due to mental illness; • 15-20% – psychophysiological, or primary, insomnia; • 10-15% – insomnia due to alcohol or drugs; • 10-15% – insomnia due to periodic motor disorders; • 5-10% – insomnia due to sleep apnea; • 5-10% – insomnia due to illness. 

In this list, the ratio of women / men is 2: 1 with a predominance of cases in lower socio-economic groups.
To fix the problem , it is necessary to collect an anamnesis (initial or average insomnia or earlier awakening) and determine the main cause: physical (e.g. pain or cough) or due to environmental factors (e.g. noise). Treatment should be focused on the root cause.   

In many cases, compliance with the sleep hygiene (such as reducing caffeine intake, changes in sleep habits or pain relief) is more preferable than the use of a sedative. Early awakening is one of the biological characteristics of depression, hence an antidepressant could be a means of choice. Insomnia without an obvious underlying reason is considered primary (psychophysiological). Serious primary insomnia is treated with sleeping pills.  

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