For decades, scientists have known two things: deep sleep is essential for recovery, and the body releases most of its growth hormone during sleep. What they did not know — until now — is exactly how the brain controls that hormone release, and how sleep and growth hormone regulate each other in a circuit.
Researchers at the University of California, Berkeley, have answered that question. In a study published in Cell, they mapped the specific brain circuits that control growth hormone release during sleep — identifying a previously unknown feedback loop in which deep sleep promotes hormone release, and that same hormone then signals the brain to shift toward wakefulness. Understanding this system provides the first clear explanation, not merely correlation, for why disrupted sleep impairs tissue repair, metabolism, and brain function.
