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Wake-activated neuronal populations that regulate sleep drive
Nature
(2026) Cite this article
Prolonged wakefulness increases sleep drive and is normally compensated for by increased sleep1,2,3. This homeostatic regulation of sleep shapes our lives profoundly, but the underlying neural circuit mechanisms remain poorly understood. Here, we identify wake-activated neurons that regulate sleep drive in mice, using whole-brain activity mapping, targeted neuronal manipulations and electrophysiology. By comparing whole-brain responses to sleep deprivation, recovery sleep and circadian behaviour, we identify the anterior medial preoptic area and the median raphe as candidate regions that encode sleep deficit. Activating sleep-deprivation-responsive cells in these regions induces increases in sleep duration and intensity that resemble recovery sleep. Conversely, inhibiting deprivation-responsive cells reduces sleep and abolishes the increased sleep propensity usually observed during deprivation. Neurons in the median raphe that are responsive to sleep deprivation project to subcortical sleep-associated regions and act through the preoptic hypothalamus. These deprivation-sensitive cells include serotonergic neurons and a distinct population of GABAergic neurons, whose intrinsic excitability increases during sleep deprivation. Co-activation of GABAergic and serotonergic neurons synergistically promotes sleep, whereas co-inhibition chronically decreases sleep by nearly 70%. Remarkably, most mice survive despite this marked reduction in sleep, without the compensatory increases in sleep drive or the behavioural deficits typically associated with severe sleep deprivation. Together, these results define neuronal populations that are activated during wakefulness and are crucial for sleep drive.
Sleep drive increases with time spent awake, and eventually becomes irresistible. Sleep deprivation leads to increased attempts to sleep, and the non-rapid eye movement (NREM) sleep that follows deprivation is longer and deeper, as measured by electroencephalogram (EEG) oscillatory activity in the delta range1,2,3 (around 0.5–4 Hz). Despite the identification of broadly distributed neural circuits that regulate sleep and wakefulness4,5,6,7, the mechanisms that generate the powerful urge to sleep remain mysterious. Human and animal studies have identified genetic loci that regulate sleep amount or EEG features of sleep8, and mitochondrial redox state, phosphorylation and secreted factors are thought to track sleep deficit9,10,11,12, but the relevant neural circuit mechanisms are poorly defined. Here, we use comprehensive activation mapping and genetically targeted manipulations to identify specific neuronal populations that regulate sleep drive.
To determine how the brain responds to prolonged wakefulness, we deprived mice of sleep for 6 h at the beginning of the light phase (the rest phase for mice) using either induced grooming behaviour or novel object exposure (Extended Data Fig. 1 and Methods). The immediate-early gene Fos labels activated neurons that control homeostatic behaviours such as feeding or drinking, and has previously revealed sleep-promoting or circadian-associated brain areas13,14,15,16,17,18,19,20,21,22,23. Accordingly, mice were euthanized for whole-brain FOS immunostaining, tissue clearing and light-sheet imaging at four time points during sleep deprivation and two time points during a 3-h recovery period, when mice exhibit post-deprivation rebound sleep (Fig. 1a and Extended Data Figs. 1 and 2). To control for stimulus-specific effects, we compared these regimes with sleep deprivation during the dark phase. In addition, we analysed 3-h circadian-time intervals to compare sleep deprivation with normal increases in sleep drive during unperturbed behaviour (Fig. 1a). After automated detection and registration of FOS+ nuclei to a common brain atlas24,25, voxel-wise clustering of FOS density across experimental time points revealed three main voxel response types d