The intense world theory of autism of Henry and Kamila Markram holds that autistic people experience the world in extreme ways. They perceive the world as so intense that it can become difficult or unbearable at times.

This theory may explain…

Sensory hypersensitivity
Stimming and self-injury as coping mechanisms
Intense feelings, including severe distress at others’ pain and meltdowns
Heightened fear

From Autism Wiki – read the full article here and watch the video below.