Sleep disorders in Parkinson's disease: Many causes, few therapeutic options

Sleep symptoms in Parkinson's disease (PD) are frequent and have multifactorial and multilayered causes. Primary involvement of sleep/wake regulating centers in the brainstem, sleep problems caused by the nocturnal manifestation of motor and dysautonomic signs and medication-induced sleep problems are often impossible to disentangle in the individual patient. Two syndromes, hypersomnia and REM sleep behavior disorder (RBD), are increasingly recognized as harbingers of the core PD motor syndrome. RBD, associated with a panoply of other nonmotor symptoms, may predispose to a specific PD phenotype. Long-acting dopaminergic stimulation, when abating nocturnal akinesia, also improves subjective sleep quantity. While this strategy is backed up by several randomized controlled trials (RCT), other treatment recommendations are mostly based on case series or expert opinion. Thus we identified only two other RCT, one treating insomnia with eszopiclone, the other nocturnal behavioral abnormalities in demented PD patients with memantine. While the causal complexity of sleep problems in PD certainly hampers the design of therapeutic studies, multiple general treatment strategies against sleep disorders can however be applied efficiently in PD patients as well.