Endorphins are endogenous opioid peptides that are produced by the pituitary gland and hypothalamus in response to stress or pain. They are released in response to physical activity, pain, laughter, and stress, and they produce a feeling of well-being and euphoria. Endorphins can reduce the perception of pain, regulate immune function, and produce feelings of relaxation and comfort. They also play a role in regulating sleep and appetite.