Recovery sleep induces analgesia via sleep ensembles of the zona incerta acting through distinct neural circuits in mice.

Recovery sleep alleviates pain in humans, yet the underlying neural mechanisms remain elusive. Here, we identify a population of sleep-activated neuronal ensembles within the zona incerta (ZI) that mediate both non-rapid eye movement (NREM) sleep and analgesia. Optrode recordings revealed preferential activity of these sleep ensembles during NREM sleep, whereas chronic pain markedly attenuated their activity. Activation of these ensembles increased NREM sleep and reduced pain sensitivity, whereas their inhibition reversed these effects. Gene profiling revealed enriched expression of neurotensin (NTS) within these neurons, and NTS knockdown significantly blunted their sleep-promoting and analgesic functions. Furthermore, ZI sleep ensembles project divergently to the lateral hypothalamus (LH) and the posterior thalamic nucleus (PO). ZI NTS projections to the LH specifically regulate NREM sleep without affecting nociception, whereas projections to the PO selectively mediate analgesia without impacting sleep. Collectively, these findings reveal that ZI sleep ensembles mediate recovery-sleep-induced analgesia, achieving modality specificity through segregated downstream targets.