Sleep dysfunction and role of dysautonomia in Parkinson's disease.

Altered sleep is a common non motor symptom in Parkinson's disease. Sleep dysfunction has been reported to occur in 60-90% of all PD patients, having a detrimental impact on quality of life and increasing disability. alpha-Synuclein deposits in the lower brainstem affecting autonomic and sleep regions have been identified in the pathophysiology. The resultant non motor symptoms such as REM sleep behaviour disorder (RBD) can precede the motor symptoms by years. RBD is violent, enacted dreams that expose the patient or their sleeping partner to night-time injuries. Excessive daytime sleepiness, sometimes with a narcolepsy-like phenotype, is a common occurrence in PD, owing to lesions in the arousal systems of the brain. Restless legs syndrome and sleep disordered breathing can all affect daytime alertness of PD patients. Autonomic deregulation can also negatively affect sleep patterns, by adding to night-time wakening and disrupting sleep.