Sleep Paralysis

, also known as hypnagogic paralysis, is a sleep disorder characterized, upon awakening or shortly before falling asleep, by a temporary inability to move and speak.
This state of paralysis is due to an excessive prolongation of the REM sleep phase, or to its early onset.
Generally, the people most susceptible to the disorder are those who sleep little and badly; however, it is not excluded that at the origin there is a serious pathology, such as narcolepsy.
Therapy varies according to the severity and number of paralysis episodes complained of by the patient.
Almost always, from a therapeutic point of view, it is sufficient to increase the number of hours dedicated to sleep and improve the quality of night rest.

, or paradoxical sleep.

Each cycle consisting of a NON-REM phase and a REM phase typically lasts 90-100 minutes.

Only the correct alternation between the NON-REM phase and the REM phase guarantees a restful rest.

NON-REM phase

The NON-REM (or NREM) phase is characterized by four stages, during which sleep becomes progressively deeper.

The first two stages are, respectively, falling asleep and light sleep; at the third stage, the phase of deep sleep begins, which reaches its climax at the fourth stage.
It is in the fourth stage of the NREM phase that the human organism regenerates itself.

The NON-REM phase is shortened with each cycle: initially, it occupies a large part of the "NREM phase-REM phase" cycle (at least for two cycles); after that, it leaves more and more room for the REM phase.

REM phase

The REM phase is a particular moment of sleep: if on the one hand there is an increase in heart rate and respiratory rate, and the individual dreams and moves his eyes rapidly (hence the acronym REM which means Rapid Eye Movement, ie rapid eye movement), on the other hand, under the influence of specific neurotransmitters, a sort of relaxation / paralysis of the musculature (muscular atony) occurs.

The REM phase initially covers a small portion of the nighttime sleep cycles; towards the morning, however, it lengthens, taking time away from the NREM phase.


Sleep paralysis is part of the list of parasomnias; parasomnia are those episodic sleep disturbances characterized by abnormal behavior or unwanted physiological events that occur during specific stages of rest or in the sleep-wake passage.

For further information: Parasomnia: What they are, Causes, Symptoms and Therapy

Is it serious?

In addition to having no repercussions on the individual, sleep paralysis is a rare episode, which occurs few times in the course of life.

However, for some subjects, it can become a recurring phenomenon, so much so as to require further checks relating to the general state of health or daily and night habits.

As will be seen later, in fact, sleep paralysis can be connected to narcolepsy, a pathology that creates sudden attacks of drowsiness, or to sleeping little and badly.

Epidemiology: How Common is Sleep Paralysis?

It is difficult to quantify how many people experience (or have experienced in the past) sleep paralysis.

According to some statistical data, in industrialized countries, about 6% of the population suffers from it. Most of these people are the protagonists of sporadic episodes, sometimes unique in the course of life.

The most affected individuals are adolescents and young adults, aged between 25 and 44 (the latter account for 36% of the sufferers).

Women and men are, in equal measure, all possible targets.

Finally, the last statistic that deserves to be mentioned concerns the relationship with narcolepsy: about 30-50% of narcoleptic people also suffer from sleep paralysis.

between the years of adolescence and about 40 years.
  • Sleeping less than you should. It is probable that those who sleep little, in the course of life, manifest phenomena of paralysis.
  • Irregular sleep, understood as going to bed and waking up at different times. This is the case, for example, of those who work on night shifts.
  • Narcolepsy. Often, narcoleptic individuals experience sleep paralysis and various other disorders during their sleep phases and throughout the day.
  • Family history. It seems that those who have a family member suffering from sleep paralysis are more prone to manifest similar phenomena. However, scientific research in this field is still in its infancy and deserves further study.
  • For further information: Sleep Paralysis - Causes and Symptoms and perceive presences or sounds that are not real.

    A classic example, described by the protagonists of such phenomena, is the feeling of not being alone in the room where you are.

    Hallucinations, if they occur in the passage from wakefulness to sleep, are called hypnagogic hallucinations; if, on the other hand, they occur upon awakening, they are defined as hypnopompic hallucinations.

    See also: Hallucinations in Sleep.

    By anamnesis, we mean the physician's collection of all information relating to symptoms and more, which help to trace the probable cause of the present symptomatology.


    During the anamnesis, the doctor carries out a real investigation, asking the patient:

    • How the paralysis evolves and how long it lasts;
    • If you have hallucinations of any kind;
    • If you remember when you were the first time victim of paralysis and if there was a change in your nocturnal habits prior to that episode;
    • If you suffer, during the day, from sudden loss of muscle control (cataplexy) or automatic behavior, that is, the inexorable and relentless continuation of the activities in which you are engaging.

    These last two aspects - cataplexy and automatic behavior - are very important for diagnostic purposes, as, if described by the patient, they could mean that sleep paralysis is the result of a much more serious pathology: narcolepsy.
    In these cases, the situation becomes pathological and must be treated with appropriate and immediate countermeasures: think, in fact, of the danger that a narcoleptic patient runs when driving a vehicle or engaged in dangerous work.

    For further information: Narcolepsy: Causes, Symptoms and Treatment.

    Sleep Paralysis: How to Sleep Well and Sufficiently

    Our body and our brain need about 6-8 hours of night sleep to stay healthy.

    In people suffering from sleep paralysis, adhering to these deadlines is essential.

    Behaviors, habits and precautions that help you sleep well and the right number of hours are:

    • Always go to bed and wake up at the same time, in order to have a regular sleep rhythm;
    • Create a cozy nighttime environment: dark, quiet room, not too hot, but not too cold either;
    • Have a comfortable bed;
    • Practice physical exercise regularly, but never shortly before bedtime;
    • Limit the consumption of caffeine;
    • Don't eat or drink alcohol just before going to bed;
    • For smokers, do not smoke before bed, as nicotine is a stimulant.
    For further information: How to sleep well: the most important rules

    Sleep Paralysis Drugs

    As anticipated, pharmacological treatment based on antidepressants is used when sleep paralysis is chronic and creates discomfort for those affected.

    The most used drug is clomipramine, a tricyclic antidepressant that must be prescribed on the recommendation of the treating physician.

    The reason for administering these preparations is as follows: they reduce the intensity with which nocturnal muscle relaxation occurs and the depth of sleep, particularly in the REM phase.

    The duration of treatment can vary from one month to two; in any case, it is the patient's improvements and above all the medical consultation that determine whether or not to interrupt the therapy.

    Tricyclic antidepressants are not free from side effects (see discussion below).

    Side Effects of Tricyclic Antidepressants

    • Dry mouth
    • Constipation
    • Excessive sweating
    • Bladder problems and difficulty urinating
    • Blurred vision
    • Sleepiness during the day

    NB: although it may seem counterintuitive (given what was previously said), drowsiness during the hours of the day is one of the typical and even more dangerous side effects of tricyclic antidepressants: think about what could happen to an individual who uses them , when he is driving a car and is seized by a sudden attack of sleep.

    Sleep Paralysis and Narcolepsy: What to Do?

    If sleep paralysis is due to narcolepsy, it is good to consult doctors with expertise in the field, as it is a serious pathological condition.

    Antonio Griguolo

    Graduated in Biomolecular and Cellular Sciences, he obtained a Specialized Master in Journalism and Institutional Communication of Science
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