Serotonin

Serotonin is a monoamine neurotransmitter synthesized in serotonergic neurons in the central nervous system and enterochromaffin cells in the gastrointestinal tract of animals including humans. As a neurotransmitter, serotonin plays an important role in the modulation of anger, aggression, body temperature, mood, sleep, human sexuality, appetite, and metabolism. Thus, an increase in serotonin levels have a calming effect, relieving depression, insomnia, and irritability. Low serotonin levels are associated with wakefulness and greater sensitivity to pain.