[Sleep and cognitive impairment in neurodegenerative diseases].

Sleep and wakefulness disorders are commonly seen in patients with Parkinson's disease, Lewy body dementia and Alzheimer's disease. Sleep provides a lot of functions which sustain normal condition of the brain and sleep disturbances can be one of the factors contributing to the development of neurodegenerative diseases. Sleep and wakefulness disorders can worsen the course of the neurodegenerative process and lead to an increase of symptoms, including cognitive dysfunction. In this review, the relationship between sleep and wakefulness disorders and cognitive impairment as well as clinical forms of sleep and wakefulness disorders and treatment methods in such patients are discussed.