This study shows that many autistic kids have a “high‑idle” nervous system and react differently to social stress, which helps explain why anxiety can be so hard to spot and manage.

Researchers measured heart activity in autistic and non‑autistic children at rest and during tasks that triggered anxiety, attention, and social understanding. Autistic children tended to have slightly higher resting heart rates (a sign of background hyperarousal) and showed different heart‑rate and calming (vagal) responses when tasks involved social evaluation and social thinking.

Within the autistic group, kids with higher IQ and better task performance showed more “typical” physiological responses to social stress, and those responses were linked to lower generalized anxiety. This suggests that autonomic patterns could help identify subgroups of autistic children and that objective, wearable measures of arousal are a promising way to support anxiety recognition and intervention when self‑report is hard.