Self-stimulatory behaviors, also called stimming, are one of the typical features of autism.
They are repetitive, stereotyped movements of the whole body (rocking, spinning) or just one part of it (flapping hands, snapping fingers, spinning objects).
Stimming is not unique to autistic people. Also typically developed persons, in some situation, use self-stimulatory behaviors. Tapping your fingers on the desk, repetitively move your foot up and down, playing with hair… they are all behaviors people normally engage in when nervous or anxious.
The reasons why people with ASD stim, may be different. In my case, I find gently rocking back and forth very calming. It just happens in stressful situations; I sit somewhere, my body starts moving and an immediate sense of calm pervades me.
Stimming may happen to reduce excessive stimulation or to increase it, it may be used to maintain focus and attention or to enhance the perception of one’s body. In case of whole body stimming, like spinning and rocking, the movements affect the vestibular sensory system, which provides the brain with information about movement and balance, our position in the surrounding space and help maintain balance and coordination.
Unless it becomes harmful, like banging the head in a wall, stimming should not be stopped. It is very important to investigate the reason behind the behavior, because it could be the result of a sensory overload that the autistic needs to reduce, or a moment of extreme anxiety which needs to be controlled. Learning to understand the reason behind self-stimulatory behaviors can be very useful also to avoid all those situations that may cause distress to the person with ASD. Sometimes stimming, used a self-regulatory behavior, is a good way to release tension and avoid a meltdown.
Many people on the spectrum say that listening to music, singing or playing an instrument, reduced their need for stimming. In many cases, music seems to produce the same effect, if not stronger, than self-stimulatory behaviors. It focuses the attention, increases or decreases (depending on the moment and the type of music) sensory stimulation. Some people feel the need to dance with music, others get a huge benefit from producing sounds. Very often, music has become a real substitute for stimming.
I remember assisting to a music therapy session with Pablo, an 11 years old autistic boy. Before the session began, he was in continuous movement, jumping, then sitting on the sofa and rocking energically, flapping his hands. Then, the music therapist started playing the piano. Within a few minutes, Pablo took a drum and started accompanying her. He sat on the sofa, visibly happy, playing his drum. During the session he also sang simple songs, danced and played other instruments.
When the session was over, he was a completely different boy, he run to his mum smiling. No sign of those frenetic movements, no need for stimming, at least for a while.