Background: Sleep deprivation causes physiologic and subjective sleepiness. Studies of fatigue effects on anesthesiologist performance have given equivocal results. The authors used a realistic simulation environment to study the effects of sleep deprivation on psychomotor and clinical performance, subjective and objective sleepiness, and mood.
Methods: Twelve anesthesia residents performed a 4-h anesthetic on a simulated patient the morning after two conditions of prior sleep: sleep-extended (EXT), in which subjects were allowed to arrive at work at 10:00 AM for 4 consecutive days, thus allowing an increase in nocturnal sleep time, and total sleep deprivation (DEP), in which subjects were awake at least 25 h. Psychomotor testing was performed at specified periods throughout the night in the DEP condition and at matched times during the simulation session in both conditions. Three types of vigilance probes were presented to subjects at random intervals as well as two clinical events. Task analysis and scoring of alertness were performed retrospectively from videotape.
Results: In the EXT condition, subjects increased their sleep by more than 2 h from baseline (P = 0.0001). Psychomotor tests revealed progressive impairment of alertness, mood, and performance in the DEP condition over the course of the night and when compared with EXT during the experimental day. DEP subjects showed longer response latency to vigilance probes, although this was statistically significant for only one probe type. Task analysis showed no difference between conditions except that subjects "slept" more in the DEP condition. There was no significant difference in the cases' clinical management between sleep conditions. Subjects in the DEP condition had lower alertness scores (P = 0.02), and subjects in the EXT condition showed little video evidence of sleepiness.
Conclusions: Psychomotor performance and mood were impaired while subjective sleepiness and sleepy behaviors increased during simulated patient care in the DEP condition. Clinical performance between conditions was similar.