The Autism Awareness Centre defines Sensory Processing Disorder like this…
SPD (formerly called Sensory Integration Disorder) is a condition where the brain and nervous system have trouble processing or integrating stimulus.
SPD is a neurophysiological condition in which sensory input – either from the environment or from one’s body – is poorly detected, or interpreted and (or) to which atypical responses are observed. For a child with SPD, processing the feelings of hot or cold, tired, hungry, lights and sound can be challenging and overwhelming.
SPD can even evoke irregular responses that can cause health issues like not registering temperature in a typical way that allows the individual to dress appropriately for health and safety’s sake. Like with autism, SPD exists on a spectrum and can affect only one sense like hearing, or taste, or all of them. As a parent, the real challenges of SPD are figuring out if your child is hurt, cold, hungry etc…and then helping them get to the point where they can regulate themselves.