German professor Alexander Lerchel stated that laughter has numerous benefits for both the soul and the body. The professor of biology and ethics at Jacobs University in Bremen explained that laughter is an effective weapon against psychological stress, sorrow, and depression; it reduces the secretion of stress hormones such as "adrenaline" and "cortisol," and helps to release the happiness hormone "serotonin." Lerchel added that laughter also contributes to deeper and faster breathing, which improves the body's oxygen supply and consequently energizes the heart and blood vessels. Moreover, laughter strengthens the immune system by activating what are known as "T cells" and gamma interferon.