Ego Depletion Is Not Just Fatigue

Abstract

Is the self-regulation failure that comes from prior exertions of self-regulation—the ego-depletion effect—the result of fatigue? A reading of the literature suggests that self-regulatory resource depletion and fatigue might be overlapping constructs, but direct empirical evidence is lacking. The authors put this question to the test by subjecting half of their participants to total sleep deprivation for 24 hours whereas others were rested; they crossed this factor with a self-regulation manipulation in which participants did or did not suppress their emotional reactions to a film. The authors' measure of self-regulation was aggressive responses in a game involving blasting noise at an opponent. Contrary to expectations, there was no effect of sleep deprivation on aggression. In confirmation of the limited-resource model, the authors found that depleted participants were more aggressive than nondepleted participants (irrespective of fatigue condition). Lax self-regulation seems to be from a lack of self-regulatory capacity, not fatigue.