The Bidirectional Relationship between Sleep and Neurodegeneration: Actionability to Improve Brain Health

Recently, it has become increasingly clear that there is a bidirectional relationship between sleep/circadian rhythms and neurodegeneration. Knowledge about this topic further improved after the description of the glymphatic system, which is mainly active during sleep. Changes in sleep and circadian rhythms are present not only in overt neurodegenerative diseases but also in their early, prodromal, and preclinical phases, supporting that they precede (and contribute to) the development of neurodegeneration. This narrative review provides a brief overview of sleep and circadian rhythm disruption in neurodegeneration, highlights the bidirectional relationship between sleep changes and neurodegeneration, and addresses future perspectives, in particular, whether sleep changes are able to predict neurodegeneration and the potential sleep actionability to prevent or modulate the development of neurodegenerative diseases.