Why do we feel the need to go to the bathroom when we’re nervous or scared?

When you’re nervous or scared, your body enters its fight-or-flight mode, controlled by the autonomic nervous system. Adrenaline levels rise, your heart races, palms sweat, and blood flow and muscle tone are redistributed to prepare you to act.

Your bladder and bowels are controlled by smooth muscle and sphincters. Stress hormones can make the bladder muscle more irritable and can loosen the sphincter. Thus you may feel your bladder is fuller than it really is or that you’re closer to leaking. Similarly, anxiety can change the pattern of contractions in the intestines and sometimes speed up movement in certain segments, producing cramps and an urgent need to pass stool.

Many researchers believe that among animals, emptying the bladder or bowels could make the body slightly lighter and more agile and may also remove internal distractions so that an animal can focus on escaping or fighting. Even if this logic isn’t complete, the fact remains that evolution has tolerated clearing waste under acute stress over a long time.

Anxiety also changes how you pay attention to bodily sensations. Sensations from the bladder and gut that you’d normally ignore become harder to do so. In people with chronic anxiety, signals travel back and forth along nerves such as the vagus nerve and stress hormones influence how sensitive the intestines are.

This is one reason irritable bowel syndrome often flares when a person is stressed: there may be more gas and more cramps even without an infection.