Claustrophobia is the fear of being enclosed in a small space or room and unable to escape. It can be triggered by many situations or stimuli, including elevators crowded to capacity, windowless rooms, hotel rooms with closed doors and sealed windows, small cars and even tight-necked clothing. It is typically classified as an anxiety disorder, which often results in panic attacks. The onset of claustrophobia has been attributed to many factors, including a reduction in the size of the amygdala, classical conditioning, or a genetic predisposition to fear small spaces.