In this article, the author describes the clinical characteristics of sleep-related rhythmic movement disorder. Sleep-related rhythmic movements are common in infants and children. The soothing effect of vestibular stimulation caused by the rhythmic movements may explain why infants rock or roll to soothe themselves. At times these movements are excessive and may disrupt sleep, resulting in daytime sleepiness or injury. In these cases, the movements are classified by the International Classification of Sleep Disorders, 3rd edition (ICSD-3), as a sleep-related rhythmic movement disorder.
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• Sleep-related rhythmic movement disorder consists of repetitive, stereotyped, and rhythmic motor behaviors (not tremor) that involve large muscle groups, such as head banging and rocking or rolling of the head or body, with a rate of 0.5 to 2 per second.
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• Sleep-related rhythmic movement disorder is distinguished from developmentally normal sleep-related movements by the presence of associated sleep disturbance, impairment of daytime function, or self-inflicted bodily injury.
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• The movements occur during bedtime or near naptime, when the patient is drowsy or asleep, and may occur during any stage of sleep, including REM sleep.
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• Sleep-related movements usually occur in infants and young children, but can also be found in adults, and the prevalence decreases with increasing age.
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• Although there are no well-established therapies, there are case reports of significant improvement of rhythmic movements and sleep quality with the use of benzodiazepines, antidepressants, behavioral interventions, hypnosis, and/or sleep restriction.
Historical note and terminology
Repetitive head banging during sleep was first described by Zappert in 1905 and termed “jactatio capitis nocturna.” At the same time, Cruchet of France termed it “rhythmie du sommeil.” The terms “head banging,” ‘head rolling,” body rocking,” “body rolling,” and jactatio corporis nocturna” have also been applied to describe the movements. This condition was named “rhythmic movement disorder” by the International Classification of Sleep Disorders (ICSD) in 1990 to include the different rhythmic movements that occur in sleep (05). It was initially classified in the parasomnia section under the subcategory of sleep-wake transition disorders because the movements were thought to occur mainly during the transition between wake and sleep.
In 2005, the International Classification of Sleep Disorders, 2nd edition (ICSD-2) renamed the condition “sleep-related rhythmic movement disorder” or “RMD” to stress that these movements are associated with sleep and to avoid confusion with the stereotypic rhythmic movements or “stereotypic movement disorder” (DSM 4 and proposed DSM 5) that occur during the daytime (04; 02). Stereotypic movement disorder consists of daytime potentially injurious, repetitive, seemingly driven, and apparently purposeless motor behavior such as hand shaking, waving, body rocking, head banging, and self-biting that cause clinically significant distress and impairment of function. The compulsions seen in obsessive compulsive disorder, tics seen in tic disorder, and stereotypies seen in children with autistic disorder are not classified as either stereotypic movement disorder or sleep-related rhythmic movement disorder.
In 2005, ICSD-2 also reclassified sleep-related rhythmic movement disorder under the new nosological category of “sleep-related movement disorders,” which includes restless legs syndrome, periodic limb movement disorder, sleep-related bruxism, sleep-related leg cramps, unspecified sleep-related movement disorder, and sleep-related movement disorder due to drug or substance or due to medical condition. ICSD-3 (03) expands “sleep related movement disorders” to also include benign sleep myoclonus of infancy and propriospinal myoclonus at sleep onset.
Interestingly, in 1937, almost 60 years prior to sleep-related rhythmic movement disorder being recognized by the ICSD, it was depicted in Walt Disney’s film Snow White and the Seven Dwarfs (31). One of the 7 dwarfs, Dopey, is noted to have repeated rhythmic back and forth myoclonus-like thrusting movements of the head, accompanied by soft vocalizations, after laying down to sleep. When he is touched, the movement subsides as he opens his eyes, and he goes back to sleep with a happy sigh.