Endorphins are peptides produced by the pituitary and central nervous system that bind opioid receptors, producing analgesia and euphoria.
Mechanism: Released in response to pain, prolonged exercise, sex, social connection, and certain foods (chocolate, capsaicin). The 'runner's high' is partially endorphins, partially endocannabinoids.
Use case: Build endorphin sensitivity via consistent aerobic exercise, breathwork, sauna, and social bonding. Don't blunt them with chronic opioid use. Receptor downregulation is real.
Caveats: Endorphins don't cross the blood-brain barrier well. Circulating measurements don't reflect central action.