Researchers are not sure of a single cause of acrophobia (an intense fear of heights). According to the Cleveland Clinic, it may grow out of a normal human concern about falling and getting hurt, especially if someone dwells on that risk. A traumatic or negative experience involving height—such as falling, watching someone fall, or having a panic attack in a high place—can also contribute.
Risk factors noted by clinicians include a personal or witnessed fall from a significant height, a panic attack while high up, and a family history of anxiety disorders. Acrophobia is a common specific phobia (roughly 3% to 6% of people) and is often treated with exposure therapy.