Figure 4.

Nonlinear mixed-effects regression model for the KSS-1 administered immediately after scheduled awakening, as estimated for the first of the three laboratory sessions, comparing awakening from different stages of sleep and after prior sleep restriction. The curves display the group model for sleepiness (KSS score) from SI after the 12-h baseline sleep period in the PSE condition or the 12-h recovery sleep period, for which the trajectories overlap (except for awakening from slow wave sleep, which only occurred after recovery sleep), and after the 6-h baseline sleep period in the PSR condition (awakening from stage 1 sleep only). Note that the scale range on the ordinate is different from that in Figure 3.