Got this as a gift for a young woman. Seratonin is a neurotransmitter involved in feelings of happiness and contentment. This is opposed to dopamine, a neurotransmitter involved in 'reward' type behavior from things like drugs, alcohol, addictive behaviors in general from feel-good behaviors. Seratonin is ling-lived, beneficial, and enduring, Dopamine is short-lived and can cause self-destructive behavior.