[Sleep and anesthesia--part 2, on the relationship between sleep and general anesthesia].

We reviewed historical and current trends on study regarding the relationship between sleep and general anesthesia. Historically, sleep has been recognized as a completely different physiological phenomenon from general anesthesia. Therefore, sleep study has been thought that it has no merit in anesthesia study. However, on the basis of recent evidence, sleep may share some part of its mechanism with general anesthesia; thus, studies focusing sleep mechanism may also contribute to elucidate some mechanism of general anesthesia. Moreover, research to solve anesthesia related-sleep disorder would be useful to improve patient's quality of life and save much medical resource.