Spiders. Airplanes. Heights. You may not even bat an eyelash reading those words, but some people freak out just thinking about these phobia-inducing subjects. And not just some people; about 19 million adult Americans have specific phobias to a variety of objects or situations [source: National Institute of Mental Health].
While panic disorder causes panic attacks in people for no identifiable reason, phobias are another type of anxiety disorder that elicits symptoms of panic attacks due to an intense fear of something specific that poses little to no danger.
And what happens when a person with a phobia encounters the object of their dread? The fear of the object or situation starts in the brain but quickly affects other parts of human physiology. Heart rate increases. Blood pressure ratchets up. And the sympathetic nervous system goes into highly active mode, which, of course, translates into what we've been talking about this whole time: excess sweat.