Basel Team IDs Sleep-Drive Neurons in Mice
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- Will Joo and colleagues at the University of Basel identified GABAergic and serotonergic neurons in the median raphe that fire more the longer mice stay awake and quiet down after sleep begins, using whole-brain Fos gene mapping across normal cycles, deprivation, and recovery sleep.
- Artificially activating both neuron populations caused mice to sleep two to three times longer than controls and spend more time in non-REM slow-wave recovery sleep — sleep that resembles the deeper rest humans get after extended wakefulness.
- Inhibiting the neurons cut sleep by about 70%, keeping mice awake roughly 6.5 extra hours per day without the anxiety-like behaviors typical of sleep deprivation — but 17% of those mice died from the lack of sleep.
- Chiara Cirelli at the University of Wisconsin-Madison called the study "outstanding" and its whole-brain Fos mapping "a real tour de force."
- The sleep-driving neurons project to the preoptic hypothalamus, a region already known to work with the median raphe to control the sleep-wake cycle.
- Mark Wu at Johns Hopkins said the work adds to growing evidence of distinct wakefulness-activated circuits that promote sleep, while Luis de Lecea at Stanford cautioned the brain has "many ways to wake up and fall asleep," pointing to separate fruit fly hints that brain mitochondria may help trigger sleep onset.
Why it matters: The study pins the elusive "sleep drive" to a specific, manipulable circuit rather than a diffuse pressure signal. The 17% mortality from inhibiting these neurons underscores how essential this mechanism is, while the deeper, longer sleep produced by activating them points to a concrete therapeutic lever — if a comparable circuit exists in humans.
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