Peptide hormones released by the hypothalmus and pituitary that activate the body’s opiate receptors, resulting in pain relief and a sense of well being. Endorphins can be secreted during exercise, laughter and orgasm. These hormones share similarities with morphine. Endorphins are also secreted when the body is being stressed or when pain is applied, such as in BDSM, which is said to result in pain reduction and euphoria. They also result in a runner’s high.