Abundant evidence suggests that people exert self-control as if the exertions consumed a limited energy resource, akin to the folk notion of willpower. After exerting self-control, subsequent efforts at self-control are often relatively feeble and unsuccessful. The state of low willpower is called ego depletion. Studies on ego depletion have shown effects on intelligent thought (which is impaired during ego depletion), decision-making (depleted persons shift to more superficial ways of choosing, or prefer to avoid making choices), and passivity (depleted people become more passive). The psychological processes of self-regulation and ego depletion are linked to physical energy, as indicated by evidence that hunger makes people more short-sighted, and that food intake tends to counteract ego depletion. Depletion increases in response to interpersonal conflict, poor sleep, and confronting uncertainty. In daily life, good self-control is linked to avoiding problems and temptations, low stress, and higher happiness.