White sugar, a carbohydrate, contains tryptophan, a precurser on the neurotransmitter called serotonin. The more tryptophan crossing the blood/brain barrier, the more serotonin the body makes. Serotonin in turn induces sleep. Studies in the American military by Bonnie Spring showed that a breakfast or lunch high in carbohydrates reduced sustained attention as mood dropped and drowsiness ensued. Out of all the sugar studies with children, the most consistent finding was decreased activity after ingesting sugar. This contradicts the hypothesis sometimes called the "Halloween effect." This theory argues that children's increased misbehavior in school after Halloween is due to their having eaten so much Halloween candy. Parents, therefore, act under a misconception when they restrict their children's sugar intake in an effort to reduce hyperactivity. Causes of misbehavior and hyperactivity must be sought elsewhere than in sugar consumption.