Physiologically, this can be a result of: (1) an imbalance of excitatory vs. inhibitory neurotransmitters, (2) an excess in "stimulants" (a coffee w/ 50mg caffeine vs. a energy drink with/ 300mg caffeine), (3) a large meal or an excess of carbohydrates causing insulin-related vasodilation,...swelling the brain, (4) some viral infections,...immune response,...vasodilation,...and swelling in the brain, (5) excessive neurological activity,...intense study, excessive social/communication, excessive emotional stress, etc.
Any one or combination of things can exacerbate the sensory symptoms,...usually due to swelling of the brain. Cerebral edema is not uncommon in the autistic population.