Neurobiology and Neuroprotective Benefits of Sleep

ABSTRACT PURPOSE OF REVIEW This article outlines the neurocircuitry underlying sleep-wake and circadian physiology with a focus on the fundamental roles that sleep and circadian health play in optimal neurologic function. RECENT FINDINGS The foundation of sleep and wake promotion is laid primarily by the “fast-acting” neurotransmitters: γ-aminobutyric acid (GABA) for sleep and glutamate for wake. External to these primary systems are a host of modulatory systems that are characterized by two flip-flop switches of mutually inhibitory neurotransmitter systems that facilitate transitions between wake and sleep as well as non–rapid eye movement (non-REM) and REM sleep. Additional mechanisms are in place to help coordinate the sleep-wake states with environmental, metabolic, and behavioral demands. The complexity of the evolutionarily preserved sleep-wake and circadian systems, the proportion of the day dedicated to the natural sleeping period, as well as the neurocognitive dysfunction and neurodegeneration caused by deficient sleep highlight the importance of defining, assessing, and optimizing the sleep health of our patients and ourselves. SUMMARY Exciting discoveries continue to elucidate the underlying mechanisms of sleep and wake state coordination, reinforcing fundamental healthy practices and paving the way for new interventions that preserve and promote optimal neurologic health.