Study objectives: To explore the effect of sleep loss on cognitive function, memory, and vigilance in resident physicians and nonphysicians and on residents' clinical performance.
Design: Meta-analysis of 60 studies on the effect of sleep deprivation, with a total sample of 959 physicians and 1,028 nonphysicians and 5,295 individual effect indexes.
Outcome measures: Cognitive performance and performance on clinical tasks under acute and partial chronic sleep deprivation. Additional analyses stratified the data by physician/nonphysician, type of performance, and length and type of sleep loss and assessed the combined effect of several of these factors.
Results: Sleep loss of less than 30 hours reduced physicians' overall performance by nearly 1 standard deviation and clinical performance by more than 1.5 standard deviations. The effect of sleep deprivation was larger in nonphysicians than in physicians (corrected d value -.995 vs -.880), with these smaller effects likely resulting from "study factors," primarily variation in the hours without sleep prior and chronically reduced sleep in the "rested" controls in physician studies.
Conclusions: The weekly hours and continuous wakefulness permitted under the current national minimum standards for residents may not completely guard against the negative effect of sleep loss on cognitive and clinical performance. Research is needed to explore the effect of continuous duty periods and chronic partial sleep loss in residents and to assess the clinical and educational consequences of sleep loss. The goal should be to combine scientifically based duty-hour limits with broader efforts to enhance patient safety and resident learning.