Rare cortical neurons synchronize brain activity and promote sleep in mice

For nearly a century, neuroscientists have probed the brain’s interior to uncover the mechanisms that trigger sleep. The prevailing model has placed deep‑seated structures—such as the hypothalamus, brainstem and thalamus—at the helm of the sleep‑wake cycle, orchestrating the transition from wakefulness to slumber. According to this view, the cerebral cortex, which underlies perception, thought and memory, functions largely as a passive recipient of signals generated by these subcortical nuclei.

Recent investigations, however, are challenging that long‑standing perspective by revealing that cortical activity may not be merely a downstream effect but could play an active role in initiating and sustaining sleep. Advanced imaging and electrophysiological studies show coordinated patterns of cortical firing that precede the classic markers of sleep onset, suggesting a bidirectional dialogue between the cortex and the deeper sleep‑regulating centers. The emerging evidence points to a more integrated network, where both deep structures and the cortex contribute to the complex process of falling asleep, reshaping our understanding of brain function during the nightly transition.