Sleep disorders are frequent in patients diagnosed with essential tremor (ET). The present review focuses on sleep disorders and the results of polysomnographic studies performed in patients with ET. For this purpose we performed a systematic review crossing the search term “essential tremor” with “sleep”, “sleep disorders”, “sleep disturbances” and “polysomnography”, and with specific sleep disorders, according to the International Classification of the Sleep Disorders-Third Edition, using the PubMed, EMBASE, MEDLINE, and Web of Sciences Databases. The most frequent sleep problems reported by ET patients were the bad quality of sleep and excessive daytime somnolence (the latter could be related to drugs commonly used for the treatment of ET). Probable REM sleep behaviour disorder, coexistent restless legs syndrome, insomnia, and nocturia were not infrequent complaints, while the presence of other sleep disorders in ET patients was restricted to anecdotal reports or not described. Meta-analyses of previous reports showed that ET patients (according to the PRISMA and MOOSE guidelines) showed higher scores in the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale than controls, and lower scores than those of patients diagnosed with Parkinson’s disease. Studies using polysomnography in ET patients are scarce and do not permit to establish valid conclusions regarding polysomnographic features in this disorder.
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