In the high 50's, though I had a minor outpatient procedure done about a year and a half ago and was told by the nurse and anesthesiologist that when I drifted off to sleep (before any anesthesia was given), I just drifted off in the holding room waiting, my heart rate dipped into the 40's. The anesthesiologist started asking me questions and I told him was a runner and fitness enthusiast. Anyway, it must be in the 40's when I sleep.