Background　Recently postoperative mortality has been found associated with cumulative anesthetic duration of low BIS（bispectral index）. It was reported that cumulative deep hypnotic time （cumulative duration of low BIS） was an independent predictor of 1-y mortality after major noncardiac surgery. Previously a few notable published randomized control trial reports confirmed the mortality-hypnosis association. These reports all derived from secondary analyses of data， which were to evaluate the effect of BIS monitoring on the incidence of intraoperative awareness. Other report found the ICU patients who under sedation experienced burst suppression had a significant higher 6-month mortality rate compared with patients who did not have burst suppression.　Objective　To discuss whether there will be a connection between cumulative anesthetic duration of low BIS and long term mortality.　Content　This review briefly demonstrates the relationship between depth of anesthesia and long term mortality.　Trend　It needs further investigation to recognize the correlation between deep hypnosis and mortality.