ABSTRACT
About 90% of neurodegenerative diseases with parkinsonism are associated with sleep disorders including daytime sleepiness, sleep-related breathing disorders and parasomnias. It is hard to define what ratio of insomnia and daytime hypersomnia is caused by the antiparkinsonian treatment, by the somatic and mental-emotional symptoms of the neurodegenerative disease and by the neurodegenerative brain process itself. Recent research suggests that the latter group is more important than expected. In Parkinson syndromes the structures included in sleep regulation--mainly within the brainstem--are also affected resulting in specific sleep disorders being the primary biological symptoms of these diseases. The recently described parasomnia--REM sleep behavior disorder--has a specific significance in this respect: it may prevent by several years a high ratio of the parkinsonian disorders--especially synucleinopathies--offering the possibility of prevention by identifying the affected individuals. There seems to exist a similar although less clarified association between daytime sleepiness and Parkinson disease. Analysing the behavior of the orexin system in neurodegenerative diseases may help to learn more about this, recently described neurohumoral system and may clear the association of narcolepsy with neurodegeneration. By understanding the associations of parkinsonian disorders and sleep disorders new therapeutical strategies may be invented and may offer new aspects to understand the mechanism of them.
