ACROPHOBIA WHAT IS IT? An extreme or irrational fear of heights. WHY CAN IT BE DANGEROUS? Sufferers can experience a panic attack in a high place and become too agitated to get themselves down safely, making them a danger to themselves or others. When placed in a situation that triggers a phobia, a person's heart rate, respiration and body temperature increase. They may become dizzy or nauseous, and they may feel faint or tremble. Mentally, they perceive the situation to be far more dangerous than reality, and their bodies react with the fight-or-flight response typical in any threat situation. While an innate cautiousness around heights might be helpful for survival, an extreme fear can interfere with the activities of everyday life, such as climbing up a flight of stairs or a stepladder.