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Parasomnias are a group of sleep disorders that cause abnormal movements, behaviours, emotions, perceptions, or dreams during sleep. These disorders affect people of all ages and can have a significant impact on their quality of life. In this article we will provide an overview of parasomnias, including their types, symptoms, causes, diagnosis, and treatment options.

There are many different types of parasomnias, which can be divided into two categories: REM (rapid eye movement) parasomnias and NREM (non-REM) parasomnias. REM parasomnias occur during the dreaming stage of sleep, while NREM parasomnias occur during the deeper stages of sleep.

REM Parasomnias can include different disorders, such as:

a) REM Sleep Behaviour Disorder (RBD): this is a condition in which the muscles that control movement are not paralyzed during REM sleep, resulting in the person acting out their dreams. The person may punch, kick, or flail their arms, and may even injure themselves or their sleeping partner.

b) Nightmare Disorder: this is a condition in which the person experiences repeated, frightening dreams that cause them to wake up in a state of terror. These dreams may involve being chased, attacked, or killed.

c) Sleep Paralysis: this is a condition in which the person is unable to move or speak during the transition between sleep and wakefulness. They may feel as though they are being held down and may experience hallucinations.

However, the most common NREM Parasomnias are:

a) Sleepwalking (Somnambulism): this is a condition in which the person walks or performs other complex behaviours while asleep, without any memory of doing so. They may appear confused or disoriented and may injure themselves or others.

b) Sleep Talking (Somniloquy): this is a condition in which the person talks in their sleep, often saying things that are incomprehensible or unrelated to what is happening in their waking life.

c) Sleep Terrors (Night Terrors): this is a condition in which the person experiences episodes of extreme fear and panic during sleep, often accompanied by screaming or thrashing about. The person may not remember the episode upon waking.

Another common NREM-related parasomnia is Sleep-related eating disorder (SRED), which is characterized by episodes of dysfunctional eating that occur after arousal from sleep. Most people with this condition show limited responsiveness during their eating episodes and have little to no memory of the events. Potential concerns include ingestion of toxic substances, injuries from cooking or preparing food, and physiological effects of unhealthy or excessive eating. 

Other types of parasomnias are:

  • Exploding head syndrome: people with exploding head syndrome hear a loud noise or feel an exploding sensation in their head when waking up. They may also perceive an imagined flash of light upon waking. This sensation can leave the sleeper with lingering feelings of palpitation, dread, and anxiety. Some people may experience multiple episodes per night.
  • Sleep-related hallucinations: this condition can involve hypnopompic hallucinations (that happen when waking up) or hypnagogic hallucinations (that happen when falling asleep). The hallucinations can include vivid images, sounds, or other sensations and sometimes can be associated with sleep paralysis. In extreme cases, sleepers may leave their bed in an attempt to escape what they are experiencing.
  • Bedwetting: also known as sleep enuresis, bedwetting refers to involuntary urination during sleep. Bedwetting is quite common in young children. To be considered a parasomnia, it must occur in someone aged 5 or older, at least twice per week, for at least three months.

Now that we know what the types of parasomnias are, what can we say about the most common symptoms? The symptoms vary depending on the type of disorder. They may include: abnormal movements or behaviours during sleep, difficulty falling asleep or staying asleep, daytime sleepiness or fatigue, memory problems, headaches, mood changes, anxiety or depression, injuries sustained during sleep and relationship problems due to disruptive sleep behaviours.

The causes of parasomnias are not well understood, but there are several factors that may contribute to their development. There is a genetic component, so that some types of parasomnias may be inherited. Other causes can be found in Sleep Disorders (parasomnias may be associated with other sleep disorders, such as sleep apnoea or restless legs syndrome), medications (some medications, such as antidepressants or antipsychotics, can cause parasomnias as a side effect), substance abuse (the use of drugs or alcohol can increase the risk of developing parasomnias) and also stress (emotional or psychological stress can trigger parasomnias in some individuals).

Although symptoms and causes of parasomnias can seem clear, diagnosing parasomnias can actually bechallenging, as many of the symptoms occur during sleep and are not observed by the person themselves. An effective way to diagnose parasomnias is a sleep study, also known as a polysomnography: during a sleep study, the person is monitored while they sleep to observe any abnormal behaviours or movements. In some cases, the person may be asked to keep a sleep diary to record their sleep patterns and any unusual behaviours or experiences.

Treatment options for parasomnias vary depending on the type and severity of the disorder. Some common treatments include medications (some medications, such as benzodiazepines, may be prescribed to help control symptoms of parasomnias), but also sleep hygiene. In fact, simple lifestyle changes, such as avoiding caffeine and alcohol before bedtime and keeping a regular sleep schedule, may help reduce the frequency and severity of parasomnias. Moreover, cognitive-behavioral therapy (CBT) and Scheduled awakenings can be valid treatments too.

Cognitive-behavioral therapy (CBT) is a type of therapy that can help individuals with parasomnias learn techniques to manage their symptoms, such as relaxation and visualization exercises.

Scheduled awakenings, instead, is a technique that involves waking the person up before the time when they typically experience parasomnia symptoms, in order to interrupt the sleep cycle and prevent the episodes from occurring.

In some cases, treatment may not be necessary if the parasomnia is mild and does not significantly affect the person’s quality of life. However, it is important to seek medical attention if the symptoms of parasomnia are causing distress or interfering with daily activities.

Lisa Nespoli



American Academy of Sleep Medicine. (2014). International Classification of Sleep Disorders, Third Edition (ICSD-3).

BMJ Best practice: https://bestpractice.bmj.com/topics/en-gb/573

National Sleep Foundation. (n.d.). Parasomnias.

Ohayon, M. M., & Schenck, C. H. (2010). Epidemiology of Parasomnias. In K. L. Chokroverty & P. B. Lopes da Silva (Eds.), Sleep Disorders Part II (pp. 499-512). Springer, New York.

Schenck, C. H., & Mahowald, M. W. (2002). REM sleep behavior disorder: clinical, developmental, and neuroscience perspectives 16 years after its formal identification in SLEEP. Sleep: Journal of Sleep and Sleep Disorders Research, 25(2), 120-138.

Sleep Foundation: sleepfoundation.org.


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