Serotonin

Serotonin is a neurotransmitter, involved in the transmission of nerve impulses. In the central nervous system, serotonin plays an important role as a neurotransmitter in the modulation of anger, aggression, body temperature, mood, sleep, human sexuality, appetite, and metabolism, as well as stimulating vomiting.

Changes in the serotonin levels in the brain can alter the mood. For example, medications that affect the action of serotonin are used to treat depression.