The fight, flight or freeze response occurs after you encounter a danger in the environment. When you sense a danger, your brain senses it and your amygdala sets off the locus coeruleus and the HPA axis (hypothalamic pituitary adrenal axis), triggering the fight, flight or freeze response. This prepares the body to either fight the threat or run from it. Freezing is a variation on the fleeing from danger, as you either escape to another location (fleeing), or you escape in the same place (freeze).
