Narcolepsy is defined in the International Classification of Sleep Disorders as “a disease of unknown etiology characterized by excessive daytime sleepiness, poor quality of night sleep, cataplexy and pathological manifestations of REM sleep, such as the appearance of short episodes of REM sleep in an awake person or” sleep attacks “,” microsleep ” , sleep paralysis, hypnagogic hallucinations. “
The prevalence of this sleep disorder in the population ranges from 0.03 to 0.16%. The disease is equally common among men and women, most likely its onset before the age of 20. There is a fairly close association of narcolepsy with certain histocompatibility antigens – HLA DR2.
The classic manifestation of narcolepsy is bouts of falling asleep during the daytime, which are difficult to resist. Patients can fall asleep while sitting in the theater, in transport and even while talking. Another important symptom is episodes of sudden loss of muscle tone, especially in emotional situations (laughing “knees buckling” is a fairly accurate metaphor), which can lead to falls. When falling asleep or on awakening, people with narcolepsy may experience or see strange images, often threatening, called hypnagogic and hypnapompic hallucinations. These sensations can be accompanied by an equally unpleasant phenomenon – a drop in the tone of the muscles of the body (the patient at this time can not move either an arm or a leg). 40% of people with narcolepsy have sleep disturbances in the form of frequent nocturnal awakenings.
The above clinical manifestations in narcolepsy are associated with disintegration syndrome, manifested by the untimely onset of sleep stages, in particular, REM sleep.
When polysomnography study identifies changes in a rapid sleep (less than 10 minutes) and early onset of REM sleep (within 20 minutes). A large number of nocturnal awakenings are also recorded.
An example of a hypnogram of a narcoleptic patient is given here.
The multiple sleep latency test can also detect shortened falling asleep time (less than 5 minutes) and early onset of REM sleep (within 20 minutes of falling asleep).
As mentioned in the definition, the causes of narcolepsy are unknown. Recent research data suggest the leading role of hypothalamic peptides, hypocretins or orexins, in regulating the correct alternation of slow and REM sleep. In patients with narcolepsy, the level of these substances in the cerebrospinal fluid is reduced .
Treatment for narcolepsy includes behavioral and drug treatments.
Behavioral includes the prevention of industrial and domestic injuries (organization of a safe environment and schedule) and the method of planned falling asleep (short periods of sleep 15-20 minutes with 2-3 hour intervals during the day).
Medicinal methods are aimed at eliminating drowsiness and cataplexy. In the first case, drugs with a psychostimulating effect ( modafinil , methylphenidate ) are effective , in the second, antidepressants of various groups (imipramine, fluoxetine). For the correction of sleep disorders, modern hypnotic drugs zopiclone and zolpidem are used .