Neurodegenerative Diseases and Sleep Disorders: The Bidirectional Relationship.

Neurodegeneration is mostly irreversible and progressive. Neurodegenerative diseases (NDDs) represent a large group of disorders that have varied clinical and pathologic representations. These include Alzheimer's disease, Parkinson's disease, vascular dementia, and amyotrophic lateral sclerosis, among others. A common factor in all these NDDs is sleep disorders (SDs). NDDs and SDs are bidirectional. Screening for SDs should be an integral part of a workup of NDDs. Management of one can improve the prognosis of the other.