Fig. 1. Brain activity patterns of wake- and sleep-promoting nuclei during states of wakefulness, sleep, and general anesthesia. BF = basal forebrain; DR = dorsal raphe nucleus; LC = locus coeruleus; LDT-PPT = laterodorsal and pedunculopontine tegmental nucleus; NREM = nonrapid eye movement sleep; PFCx = prefrontal cortex; PHA = posterior hypothalamic area; PRF = pontine reticular formation; REM = rapid eye movement sleep; vlPAG = ventrolateral periaqueductal gray; VLPO = ventrolateral preoptic area. Adapted with permission from Vanini G, Baghdoyan HA, Lydic R: Relevance of sleep neurobiology for cognitive neuroscience and anesthesiology, Consciousness, Awareness, and Anesthesia. Edited by Mashour GA, Cambridge University Press, 2010.