Purpose of review: The aim is to review sleep disturbances in different movement disorders, mainly Parkinson's disease, and highlight current concepts on merging the boundaries between movement disorders and dissociative states of being.
Recent findings: Since the observation that rapid eye movement sleep behavior disorder (RBD) may be an early marker of neurodegeneration, many studies focused on this disorder for the opportunity to explore the pathogenetic mechanisms underlying movement disorder and future neuroprotective therapies. It is also increasingly evident that this disorder is a possible marker for incoming dementia and for a general worst prognosis. Mechanisms of excessive daytime sleepiness in Parkinson's disease are still to be clarified and, if the role of hypocretin neuron loss is still doubtful, attention is moving to the role of monoaminergic system disruption. The role of dopamine in circadian rhythm regulation is opening new scenarios, namely the disruption of clock genes expression. Finally, the close relationship between sleep and movement disorder is emerging also in primarly sleep disorders.
Summary: Recent studies provided new insights into the links between sleep and movement disorder that may simplify the diagnostic process and shed light on the underlying pathophysiological mechanisms.