Sitting still requires the active suppression of the motor system — a PFC computation that consumes significant cognitive energy. For many children with ASD (especially with ADHD comorbidity), this "stillness" computation costs so much that nothing remains for the actual task. The paradox: demanding stillness reduces attention. Allowing movement increases attention. The body must move so the brain can think.

Fidgeting provides sub-threshold sensory stimulation that maintains arousal in the alerting network. Research shows children with ADHD who fidget more perform better on cognitive tasks. The fidget provides just enough input to keep the brainstem reticular formation activated — maintaining the "on" state. Taking away the fidget is like cutting the engine's idle: the system stalls.

Attention difficulty in ASD reflects the interest-driven nervous system: the reward system (nucleus accumbens) determines attentional allocation. Preferred topic = high dopamine = unlimited attention. Non-preferred task = low dopamine = attention collapses. This is NOT voluntary. The child cannot "choose" to find math interesting any more than you can choose to find a blank wall fascinating.

Distractibility reflects a filtering deficit in the thalamic gating system. Normally, the thalamus acts as a sensory gate — filtering irrelevant input and passing only relevant information to the cortex. In ASD+ADHD, this gate is too open: everything gets through. The brain cannot determine which stimuli are relevant (teacher's voice) vs. irrelevant (traffic outside). ALL stimuli arrive at the cortex with equal priority.

Impulsivity = PFC inhibitory failure. The PFC should: detect the impulse → evaluate the consequence → inhibit the motor response → generate an alternative. This entire computation should happen in 200–500 milliseconds. In ASD+ADHD, the PFC computation is too slow — the motor cortex fires before the PFC can evaluate and inhibit. The child is not choosing to be impulsive; the brake is too slow for the engine.

Sleep initiation requires four simultaneous conditions that are each harder in ASD: melatonin release (often reduced or delayed), arousal system deactivation (difficult when anxiety or sensory issues maintain sympathetic activation), PFC executive shutdown (the thinking brain must quiet — hard when thoughts loop), and sensory comfort (body must reach sensory neutrality — nearly impossible when bedding, temperature, or noise are aversive).

Sleep cycles include brief natural awakenings between 90-minute NREM/REM cycles. Neurotypical children briefly wake → self-soothe → return to sleep without full consciousness. ASD children wake → fully activate (sensory system online, arousal system engaged) → cannot self-soothe → fully awake for hours. Reduced melatonin + anxiety + sensory alertness = cycle after cycle of complete waking.

Bedtime resistance reflects multiple converging factors: transition difficulty (ending preferred activity is aversive), separation anxiety (leaving parent), fear of dark, FOMO, and most importantly — conditioned avoidance. When bedtime has been paired with frustration and demands repeatedly, the bed itself becomes an aversive stimulus. The child is not being difficult; they are avoiding something their nervous system has learned to associate with distress.

A sleep routine builds a conditioned chain in the basal ganglia: step 1 → step 2 → step 3 → ... → sleep. After enough repetitions, the chain becomes automatic — each step triggers the next, and the final step triggers sleep onset. The brain begins melatonin release not at a clock time, but at the start of the routine — because the routine has become the brain's primary sleep cue. One disrupted night begins to reset the chain.

A consistent bedtime routine is the #1 sleep recommendation for ASD across all major clinical guidelines — NCAEP 2020, AAP sleep guidelines, and every major sleep-in-ASD meta-analysis. No other single intervention has stronger consensus.

Sleep requires the sensory system to reach a state of sensory neutrality — neither over-stimulated nor under-stimulated. For the ASD sensory system, this neutral zone is extremely narrow. Achieving it requires simultaneous optimisation of six sensory channels: visual, auditory, tactile, temperature, proprioceptive, and olfactory. All six must be addressed — optimising five while leaving one problematic can prevent sleep entirely.

Sensory sleep environment optimisation is supported by NCAEP 2020, sensory processing and sleep research, and the clinical consensus across OT, sleep medicine, and ASD-specialist practice globally.