In addition to turning wakefulness off, anesthesia drugs turn on the brain's natural sleep circuitry, according to new research conducted in mice (Moore JT et al. Curr Biol. doi: 10.1016/j.cub.2012.08.042 [published online October 23, 2012]).
Through staining experiments and electrophysiological studies, scientists from Children's Hospital of Philadelphia and the University of Pennsylvania found that the anesthetic drug isoflurane boosts activity in the ventrolateral preoptic nucleus (VLPO), a sleep-promoting brain area within the hypothalamus. Both natural sleep and anesthetic-induced unconsciousness produced similar increases in numbers of active neurons in this region.
Hampton T. Anesthesia and Sleep Circuits. JAMA. 2012;308(22):2326. doi:10.1001/jama.2012.77558