Sleep dysfunction in Parkinson's disease

The frequency of sleep complaints in patients with Parkinson's disease (PD) is estimated to be between 60-90% and a variety of either disease-related or secondary mechanisms and the dopaminergic treatment itself contributes to the development of different sleep disturbances. These comprise slight, fragmented sleep with increased number of arousals and awakenings, and PD-specific motor phenomena such as nocturnal immobility, rest tremor, eye-blinking, dyskinesias, and other phenomena such as periodic and nonperiodic limb movements in sleep, restless legs syndrome, fragmentary myoclonus, and respiratory dysfunction in sleep. Depression and hallucinations/psychosis further complicate the picture. The incidence of REM sleep behavior disorder (RBD) with nightmares and violent behavior is increased in PD and may occur as a preclinical disease-related symptom. A careful sleep history of patients and their partners, polysomnograms when necessary, motor and psychiatric assessments should precede individual treatment strategies, which include adjusting dopaminergic daytime treatment, benzodiazepines for RBD, reduction of anticholinergic drugs, and, if necessary, clozapine for nocturnal psychosis.