Parasomnias are abnormal behaviors emanating from or associated with sleep. Sleepwalking and related disorders result from an incomplete dissociation of wakefulness from nonrapid eye movement (NREM) sleep. Conditions that provoke repeated cortical arousals, or promote sleep inertia lead to NREM parasomnias by impairing normal arousal mechanisms. Changes in the cyclic alternating pattern, a biomarker of arousal instability in NREM sleep, are noted in sleepwalking disorders. Sleep-related eating disorder (SRED) is characterized by a disruption of the nocturnal fast with episodes of feeding after an arousal from sleep. SRED is often associated with the use of sedative-hypnotic medications; in particular, the widely prescribed benzodiazepine receptor agonists. Recently, compelling evidence suggests that nocturnal eating may in some cases be a nonmotor manifestation of Restless Legs Syndrome (RLS). rapid eye movement (REM) Sleep Behavior Disorder (RBD) is characterized by a loss of REM paralysis leading to potentially injurious dream enactment. The loss of atonia in RBD often predates the development of Parkinson's disease and other disorders of synuclein pathology. Parasomnia behaviors are related to an activation (in NREM parasomnias) or a disinhibition (in RBD) of central pattern generators (CPGs). Initial management should focus on decreasing the potential for sleep-related injury followed by treating comorbid sleep disorders. Clonazepam and melatonin appear to be effective therapies in RBD, whereas paroxetine has been reported effective in some cases of sleep terrors. At this point, pharmacotherapy for other parasomnias is less certain, and further investigations are necessary.Keywords Parasomnia . Sleepwalking . Sleep terrors . REM sleep behavior disorder . Restless legs syndrome
Classification of ParasomniasParasomnias are typically classified by the sleep state from which they arise: non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM) (see Table 1 NREM parasomnias include: confusional arousals, sleepwalking disorder, and sleep terrors. These behaviors arise when the cortex incompletely arouses from deep NREM sleep, often due to comorbid conditions that provoke repeated arousal or promote sleep inertia. Changes in the cyclic alternating pattern, a biomarker of arousal instability in NREM sleep, are noted in sleepwalking and related disorders [3].Sleep-related eating disorder (SRED) is currently classified in the International Classification of Sleep Disorders, 2nd edition (ICSD-2) under "Other Parasomnia" [1]. However the vast majority of SRED cases emanate from NREM [4], and the complex amnestic behaviors with ambulation are striking similar to sleepwalking [5]. Furthermore, both SRED and sleepwalking are frequently triggered by sedating agents in the setting of underlying motor restlessness [6]. Thus, considering these similarities, SRED will be reviewed immediately after NREM parasomnias.REM sleep behavior disorder is the most clinically relevant REM parasomnia. The loss of atoni...