(3) Serotonin:The third hormone Serotonin is released when we act in a way that benefits others.Serotonin is a compound present in blood platelets and serum, which constricts the blood vessels and acts as a neurotransmitter.Serotonin is a chemical that carries messages between nerve cells in the brain and throughout your body. Serotonin plays a key role in such body functions as mood, sleep, digestion, nausea, wound healing, bone health, blood clotting and sexual desire.Typically, nerve cells in the brain and spinal cord produce serotonin that helps regulate attention, behavior and body temperature. Other nerve cells in the body, primarily in