Purpose: To assess the levels of physiologic and subjective sleepiness in residents in three conditions: (1) during a normal (baseline) work schedule, (2) after an in-hospital 24-hour on-call period, and (3) following a period of extended sleep.
Method: In 1996, a within-subjects, repeated-measures study was performed with a volunteer sample of 11 anesthesia residents from the Stanford University School of Medicine using three separate experimental conditions. Sixteen residents were recruited and 11 of the 16 completed the three separate experimental conditions. Daytime sleepiness was assessed using the Multiple Sleep Latency Test (MSLT).
Results: MSLT scores were shorter in the baseline (6.7 min) and post-call (4.9 min) conditions, compared with the extended-sleep condition (12 min, p =.0001) and there was no significant difference between the baseline and post-call conditions (p =.07). There was a significant main effect for both condition (p =.0001) and time of day (p =.0003). Subjects were inaccurate in subjectively identifying sleep onset compared with EEG measures (incorrect on 49% of EEG-determined sleep episodes).
Conclusion: Residents' daytime sleepiness in both baseline and post-call conditions was near or below levels associated with clinical sleep disorders. Extending sleep time resulted in normal levels of daytime sleepiness. The residents were subjectively inaccurate determining EEG-defined sleep onset. Based on the findings from this and other studies, reforms of residents' work and duty hours are justified.