In decision making and psychology, decision fatigue refers to the deteriorating quality of decisions made by an individual, after a long session of decision making. It is now understood as one of the causes of irrational trade-offs in decision making.For instance, judges in court have been shown to make poorer decisions later in the day. Decision fatigue may also lead to consumers making poor choices with their purchases.
The brain, like the rest of the body, derived energy from glucose, the simple sugar manufactured from all kinds of foods. To establish cause and effect, researchers at Baumeister’s lab tried refueling the brain in a series of experiments involving lemonade mixed either with sugar or with a diet sweetener. The sugary lemonade provided a burst of glucose, the effects of which could be observed right away in the lab; the sugarless variety tasted quite similar without providing the same burst of glucose. Again and again, the sugar restored willpower, but the artificial sweetener had no effect.1