Researchers have identified a rare group of cortical neurons that can help initiate sleep, challenging the view that sleep is controlled solely by deeper brain regions. Activating these Sst-Chodl neurons in mice induced sleep, suggesting the cerebral cortex can generate and broadcast signals sufficient to promote the brain’s slow rhythms.

The cells comprise roughly 0.1% of cortical neurons, making them difficult to isolate, and required a technique targeting two genes simultaneously. Despite their scarcity, individual neurons form extensive connections across regions involved in vision, touch, hearing, memory, navigation and movement. Of 111 cells observed, 95 became active during slow-wave sleep and quiet wakefulness, but not during running or REM sleep; their activity also differed markedly from surrounding neurons during transitions between active and silent brain states.