This is a category of sleep disorders that involves abnormal and unnatural movements, behaviors, emotions, perceptions, and dreams that occur while sleeping, during the phases of sleep or sleep deprivation. Most parasomnias are dissociated sleep states that are partial arousals during the transition between wakefulness and REM or non-REM (NREM) sleep. The presenting symptoms tend to be related to the behavior itself. They are more common in children, although they may persist into adulthood, in which case they have a more pathological significance


Nightmares are a frequent phenomenon in children, with a prevalence of 10% to 50% between ages 3 and 6. They are described as dreams with frightening content, which usually occur during REM sleep, mainly in the second half of the night, and which end up awakening the child. The awakening occurs quickly, not presenting the typical state of mental confusion of night terrors. Agitation (palpitations, increased respiratory rate, sweating, etc.) is less marked in nightmares. The child can recount a detailed memory of the content of the dream.

If the nightmares are intense and frequently repeated they may have a negative effect on the day to day life of the patient. Despite being most frequent in children, they can also occur in adulthood. Situations of stress and traumatic episodes increase their frequency and severity. In the treatment of this problem, relaxation techniques and confrontation of the contents of the nightmare are used, which solves the problem in a short amount of time.


In adults, nightmares are sometimes linked with both medical and psychological illnesses, and even some medications. Several studies have studied the role of medications in the emergence of nightmares. A review carried out by researchers from the University of Colorado – published in 2003 in Human Psychopharmacology – summarizes major drugs that generate this type of problem. From a large list, some stand out as might be expected, such as antidepressants like Prozac or Seroprac, hypnotics like Noctamid or Stilnox, and anti-Parkinson medications like Sinemet. However, among the medications that increase the number of nightmares are also other less expected ones such as the antibiotic ciprofloxacin, painkillers like naproxen, or statins like Lipitor. In this list of about 50 products, medications for cardiac disorders (atenolol, or propranolol) and antiretrovirals (Sustiva) also show up.


Children suffering from this disorder awaken in the first third of the night (phases III and IV of sleep), with a strong shout and important signs of autonomic activation (tachycardia, sweating, etc.). Parents will respond to their cries and, after awakening them, observe that they have difficulty responding and are not aware of what happened. Unlike nightmares, they do not remember the content of their dream in the morning. They are more common in childhood (3-5 years old), with a tendency to disappear in adolescence.


Sleepwalking is a disorder that usually occurs in the first third of the night (phases III and IV), causing awakenings, in which the person can perform simple acts (sitting in bed), or more elaborate ones (going to another room in the house, hiding, trying to open the front door). The person does not respond to external stimuli and is not easily woken by others. The sleepwalker should not be awokenonly accompanied to bed. If the person is woken up, he or she will be confused, but will not show cognitive or behavioral alterations. The next day the person will not remember the episode. Like other parasomnias, it is common in childhood and tends to disappear in adolescence, although it can be observed in adults between 18 to 35 years old. There are no gender differences.

It is advisable to adopt precautionary measures to prevent accidents, such as avoiding keeping hazardous objects in the room as well as closing doors and windows. In severe cases, medication is prescribed.



In children, sleepwalking also appears during deep sleep (stage III and IV). The child gets up from bed and does simple activities learned during the day, washing hands, sitting in a chair and then goes back to bed. The older they are, the more difficult it is to guide them to bed and the more they tend to continue doing things their way. Sometimes, they will end up sleeping in a room other than their own. Although sleepwalking is not dangerous in itself, it may sometimes lead to accidents if the child stumbles on an object, tries to climb out of a window, or open the door of the house.

Awaking the child should be avoided as it will only create a situation of surprise since they do not understand why they are being woken. Because of the tendency to misinterpret the environment, if they are touched, it can increase the degree of agitation in older children. It is usually easy to redirect them to bed, without waking them up.



REM sleep behavior disorder (RBD) is a behavioral disorder associated with the REM phase of sleep, characterized by acting out violent dreams with diverse movements. It usually appears an hour and a half from the beginning of sleep, possibly with several episodes throughout the night. It is more common in men and usually appears after the age 60, although it can occur at any age. Due to the serious consequences that may result (self-harm and injury to bed partner), it is important to consult a specialist. Occasionally, it is the prelude to a neurological disease so one should be evaluated and undergo medical monitoring.


This disorder involves emitting verbal sounds without full meaning during sleep. The sounds are often related to dreams.

It is more common in males and usually appears in childhood, although it can occur at any age. When the problem is maintained into adulthood, it tends to be associated with stressful situations, episodes of fever, and other sleep disorders, such as apnea and night terrors. There is no specific treatment for it.



This disorder is characterized by a rhythmic activity of the muscles of mastication, causing wear and tear of the teeth. When it takes place during sleep, the person is not aware of this behavior, and they tend to wake up with jaw pain. Stress and anatomical problems can play an important role in the origin of this disorder. Night mouth guards are commonly used, which prevent the teeth from touching, as well as relaxation and biofeedback techniques to learn to relax the muscles involved.


Hypnic myoclonia is defined as sudden and brief involuntary contractions of muscle groups. They mainly affect the legs, though they may be seen in the arms and even the head. They appear when falling asleep and have no clinical significance. They are related to the intake of nicotine, caffeine, heavy exercise, and stress. If they are very frequent or intense, the stimulating triggers will be withdrawn and behavioral measures will be carried out. Medication is rarely necessary for their treatment.


Confusional arousals are described as awakenings throughout the night, most frequently when sleep is deep, when the person wakes up suddenly, confused and disorientated in time and space. The behavior is often inappropriate, with misunderstandings and errors of logic. The episode may last several minutes. It is seen most frequently in children and disappears with time. In principle not much importance needs to be given to it, but precipitating factors such as stimulants, depressants of the central nervous system or stress do need to be avoided.


Sleep paralysis occurs during the REM phase of sleep. If it appears as an isolated symptom, it is not very important. In a characteristic way, the person cannot move any part of their body except the eyes and diaphragm to breathe. It is a situation that causes anguish and in which the patient must maintain control, since it does not present any danger and after a few seconds or minutes (1-3 min), it will pass without consequences. If another person touches them, it will disappear spontaneously. It appears more frequently in shift workers or in people suffering from periodic jet-lag.

RHYTHMIC MOVEMENT DISORDERS (rhythmic movements during sleep)

Rhythmic movement disorders are characterized by sudden, repetitive involuntary movements of various parts of the body in children when they are falling asleep. They can take the form of anterior-posterior movements, lateral rotation of the head, longitudinal trunk rolling, etc. They are frequently accompanied by guttural sounds, which are bothersome for the whole family. It usually occurs during the transition between wakefulness and sleep, although in some children it can also occur in other types of sleep (slow wave sleep and REM sleep). They rarely last more than 15 minutes.

The stereotyped movements usually start before the ninth month of life and rarely after 2 years of age. The presence of rhythmic movements is not related to neuropsychiatric alterations. It frequently occurs in physically and neurologically normal children. However, it is not rare that children with mental retardation experience them, without the need for any therapeutic measures.

These movements are the cause of worry in parents, but should be considered a benign disorder, which improves on its own over time. Steps can be taken to reduce the noise and prevent the child from hurting him or herself physically. When these movements persist until late childhood or adolescence, a neurological or psychological problem should be suspected.