Nervousness or anxiety shuts off the part of the brain that controls urination, according to CalmClinic. Anxiety overloads the nervous system, putting the body in a fight or flight mode, which overwhelms the brain's ability to coordinate the body system.
Nervousness causes two types of urination: immediate urination and frequent urination, according to CalmClinic. Immediate urination results from severe phobias or fear. The most likely cause of frequent urination is muscle tension. Anxiety causes muscle tension that puts pressure on the bladder causing a urinating sensational. Progressive muscle relaxation exercises and avoiding drinks and foods that increase urination help control anxiety-caused urination.