Parasomnias – Night Terrors, Sleep Walking & Nightmares



Parasomnias are unusual episodes or behaviours occurring during sleep which disturb the patient or others; here we addresses those that cause significant distress and therefore present for treatment. Assessment of parasomnia may be possible with a detailed history from the patient or a witness but, in general, for an adequate diagnosis referral to a specialist sleep centre for polysomnography (PSG) and video recording may be necessary. Violent or unusual night-time attacks may arise from deep  non-REM sleep (night terrors and sleepwalking) or from REM sleep (severe recurrent nightmares, REM behaviour disorder), and treatments depend on which disorder is present.

Night Terrors (Sleep Terrors)

Night terrors (also called sleep terrors) are recurrent episodes of abrupt awakening from deep non-REM sleep, usually in first third of the night, usually with a scream and signs of intense fear and autonomic arousal. The patient is unresponsive to comforting; they may sit up in bed and sometimes engage in automatic behaviour associated with fear and escape. There is usually no detailed recall, and if the patient wakes from a terror (not common), there is confusion and disorientation and only a vague memory of fear. Night terrors are common in children, with about 30–40% having at least one episode, and repeated episodes in about 5%. The peak age for these is at about 2–7years, with a gradual diminution up to early adolescence (DiMario and Emery, 1987). In some cases night terrors persist into adult life; the prevalence in adults is unknown. Almost all adult patients have had night terrors or sleepwalking as a child (Crisp, 1996). There is a strong genetic component (Nguyen et al., 2008), and night terrors and sleep-walking in the same patient is fairly common.


Sleepwalking alone probably has 15–20% lifetime prevalence. The main symptom is of automatic behaviour at night with the sufferer unresponsive to surroundings and other people. The behaviour is most commonly walking around, but can include other behaviours which are highly familiar to the subject such as dressing, washing, making tea, arranging objects in the house, etc. Some cases of sleepwalking seem related to use of certain drugs, for example alcohol and hypnotics, especially zolpidem and triazolam (Pressman, 2007). It is rare for affected individuals to present for treatment, except if they have injured themselves or a partner, have put themselves into potential danger, or have excessive daytime fatigue because of nighttime disturbance. Another reason for presentation is anxiety and disruption of sleep of partner, family or housemates.


Nightmares and REM sleep behaviour disorder (RBD) are disorders arising from REM sleep, and the main difference in presentation from the non-REM episodes is that they are normally recalled by the patient, who wakes from them and is aware of the episode and can describe it. RBD is a disorder, first described in the late 1980s, with violent complex behaviour at night, which is mostly recalled by the patient. There are two sleep abnormalities; lack of atonia during REM sleep, and increased vividness and/or unpleasant content of dreams. The violent behaviour is described as ‘acting out of dreams’, made possible by the lack of the normal muscle paralysis in REM sleep. Its incidence is unknown (probably<1%), it occurs in older people with a steady rise after 55years of age, and has a marked male preponderance. It may be idiopathic but much more often is associated with Parkinson’s disease (it is seen in up to 50% of patients with Parkinson’s disease), Lewy body dementia (70%), and multiple system atrophy (>90%). RBD may be the first manifestation of these disorders, antedating the onset of parkinsonism, cerebellar syndrome, dysautono-mia, and dementia by several years (Gagnon et al., 2006)
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