Effects of Acute Partial Nocturnal Sleep Restriction on Mental Fatigue and Cognitive Control

This study examined how one night of 5 h partial sleep restriction affects mental fatigue and cognitive control and compared the magnitude of change between subjective and objective measures. In a within-subject crossover design, 32 healthy university students completed the Stanford Sleepiness Scale (SSS), a visual analog scale (VAS) of fatigue, the brief Psychomotor Vigilance Task (PVT-B), and a modified Stroop task under a normal-sleep condition and a one-night 5 h sleep-restriction condition. Data were analyzed with linear and generalized linear mixed models. Sleep restriction significantly increased subjective sleepiness and fatigue (both p < 0.001; ηp2 = 0.69 and 0.71, respectively), and these increases were already present before the task. It also produced a small decline in Stroop accuracy for congruent trials (95.94% vs. 93.86%; OR = 0.65, p < 0.001) and special trials (80.40% vs. 76.62%; OR = 0.80, FDR-corrected p = 0.038), with no significant change in incongruent-trial accuracy or reaction time. Objective vigilance and overall reaction time did not change significantly. One night of mild sleep restriction was therefore sufficient to induce subjective mental fatigue; the only objective effect detected was a small decline in accuracy for congruent and special trials, whereas objective vigilance and overall reaction time showed no significant change. The early effects of mild sleep loss appear subjectively sensitive, while the objective cognitive effects, if any, are small and confined to congruent- and special-trial accuracy.