Scientists pinpoint wake-active brain cells that drive the urge to sleep
Researchers identified specific neurons in the median raphe and anterior medial preoptic area that become active during wakefulness and control sleep pressure in mice.
The study combined light-sheet imaging of Fos expression, targeted viral labeling, and patch-clamp recordings to map brain-wide responses to six-hour sleep deprivation in mice. Three response patterns emerged, and the wake-correlated type highlighted the median raphe (MR) and anterior medial preoptic area (aMPO) as key hubs encoding sleep deficit. Chemogenetic activation of deprivation-TRAP cells in these regions induced prolonged, high-intensity NREM sleep resembling natural rebound, whereas inhibition reduced baseline sleep and eliminated the usual increase in sleep propensity during deprivation.
Within the MR, GABAergic (Vgat+) and serotonergic (Sert+) neurons showed heightened excitability after sleep loss and synergistically drove sleep when co-activated; their glutamatergic (Vglut2+) counterparts promoted wakefulness. Chronic silencing of both GABAergic and serotonergic populations with Kir2.1 lowered NREM sleep by almost 70%, extended wake bouts, and prevented delta-power accumulation, yet most mice survived and retained normal memory performance. These findings define wake-activated neuronal ensembles that are essential for generating and regulating sleep drive.
Why it matters
Understanding the neural circuits that create sleep pressure could lead to new treatments for insomnia and other sleep disorders.
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