Many autistic children have Sensory Processing Disorders. (And so do children with Down's Syndrome, ADHD and other or no other conditions). Their sensory systems (as above) can be hyper (over) or hypo (under) sensitive and this affects the way that they understand, perceive and interact with the world around them. It also affects their perception of their own bodies and how they function. And I'm often asked whether the sensory responses can be different on different days – yes, they can. Some sensory responses can be hyper and some hypo – in the same person.