Figure 1. Impact of sleep, central, and peripheral circadian rhythms on brain homeostasis.

The SCN synchronizes circadian rhythms in the cellular clocks of cells in the brain, the sleep wake cycle, and peripheral organs. Cellular clocks within neurons and glia in turn regulate transcription of genes involved in critical processes such as redox homeostasis, inflammation, proteostasis, and metabolism. Sleep influences many of the same pathways, perhaps in some cases through interaction with the clock. Circadian regulation of peripheral metabolism, inflammation, and hormone secretion also impacts the brain.