Studies consistently show that total sleep deprivation (TSD) and measures of performance are negatively correlated. However, an accurate quantitative summary of the relationship between these variables has not yet been reported. After collection of the data from 27 relevant studies, meta-analytic techniques were used to test several hypotheses. The correlations were found to be highest for TSD of greater than or equal to 45 h, speed rather than accuracy measures of performance, and work-paced rather than self-paced tasks. These findings are consistent with the "lapse hypothesis" that posits microsleeps during long hours of sleep deprivation.