What is stimming?
 
Stimming is almost always a symptom of autism, but it's important to note that stimming is also a part of most people's behavior patterns. If you've ever tapped your pencil, bitten your nails, twirled your hair, or paced, you've engaged in stimming. Like anyone else, people with autism stim to help themselves to manage anxiety, fear, anger, and other negative emotions. Like many people, people with autism may stim to help themselves handle overwhelming sensory input (too much noise, light, heat, etc).