Sensory Processing Disorder (SPD) — formerly referred to as sensory integration dysfunction — is a neurological condition that interferes with the body’s ability to interpret sensory messages from the brain and convert those messages into appropriate motor and behavioral responses.
It's not uncommon to feel occasional sensory overload — that is, to feel overwhelmed by distracting noises or crowded spaces or strong odors once in a while — but for children with SPD, these sensations disrupt and overwhelm everyday life.
Sensory Processing Disorder may make it difficult to filter out unimportant sensory information, like the background noise of a busy school hallway, and causes children to feel overwhelmed and over-stimulated in certain environments.
Or SPD may make it difficult to take in important sensory information; a child who has tripped may not react quickly enough to soften her fall, for example.