Pituitary gland: stimulates production of endorphins / balances hormone secretions of many other glands (mindbodygreen.com)
Slowed breathing also is associated with increased production of endorphins, those wonderful internal chemicals that improve our sense of wellbeing. (mindbodygreen.com)
Cartmel cited other research that said exposure to ultraviolet light triggers production of endorphins, a «feel good» hormone. (health.com)