Dexmedetomidine (DEX) induces a distinct state of “arousable sedation,” yet the neural circuits that sustain arousal capacity remain unclear. Here, we identified that 40 μg/kg DEX produced sedation from which animals could be transiently aroused by tactile stimulation of the back, whereas 100 μg/kg induced deeper, unresponsive sedation. Functional mapping revealed selective activation of the central medial thalamus (CMT). Fibe...