Sensory processing disorder—also known as SPD or sensory integration disorder—is a widely debated term describing a collection of challenges that occur when the senses fail to respond properly to the world around them. The five external senses of vision, hearing, touch, taste, and smell—as well as the internal vestibular, interoceptive, and proprioceptive senses—are critical for interacting with the environment. When the sensory receptors in the nervous system malfunction, as they’re theorized to do in SPD, common stimuli like lights, noises, and textures may be perceived as too bright, too loud, or too uncomfortable. Sensory processing issues may also manifest as input-related challenges, resulting in sensory-seeking behaviors compensating for low levels of tactile or proprioceptive input.
While most researchers agree that sensory challenges exist, and can be serious, whether or not these issues can be classified as their own disorder has been contested. SPD was not included in the latest edition of the DSM—rather, sensory issues were listed as a possible symptom of autism spectrum disorder—and it was also left out of the ICD-11. But while many children and adults who have sensory integration challenges also have autism (or ADHD, another condition with ties to sensory challenges), many parents and adults continue to advocate for SPD to be recognized by major psychological organizations as a distinct entity.