An emerging link between general anesthesia and sleep

Two of the most enigmatic and challenging problems in neuroscience are the search for the function of sleep and understanding the mechanism by which volatile chemicals can induce general anesthesia. Despite the apparent similarity of sleep and anesthesia to the neophyte, it is widely argued that these brain states are actually apples and oranges, sleep being readily reversible (thankfully), whereas anesthesia is irreversible. In a recent issue of PNAS, Kelz et al. (1) demonstrate that disruption of a specific neural locus involved in normal sleep–wake regulation selectively affects emergence from, but not induction of, general anesthesia. That article demonstrates that waking up from anesthesia uses neural circuits distinct from those necessary to become anesthetized. It also further solidifies the connection between anesthesia and sleep, implicating wake-promoting neural circuitry in selectively contributing to emergence from anesthesia.