Correlation between the Epworth Sleepiness Scale and the Maintenance of Wakefulness Test in patients with narcolepsy participating in two clinical trials of sodium oxybate

Although all correlations showed statistical significance, they were of low-to-moderate strength. These results indicate that ESS and MWT measure features of pathologic sleepiness that may be distinct, but partially overlapping. These data corroborate those of other studies, suggesting that physiologic mechanisms that regulate alertness and sleep propensity may function somewhat independently.