This study investigated whether individuals with autism exhibited consistent patterns of physiological hyperarousal associated with chronic mobilization, particularly when exposed to social stimuli. Previous research provided inconsistent findings on autonomic activity in autism. To address this, the present study investigated potential underlying factors by comparing the influence of distinct stimuli on physiological arousal across repeated measurements. A sample of 58 adults (29 with and 29 without autism) participated in three sessions, involving resting and social conditions. Physiological arousal was measured using photoplethysmography, from which heart rate, heart rate variability, and respiratory sinus arrhythmia were derived. It was hypothesized that participants with autism would exhibit physiological hyperarousal at rest, associated with chronic mobilization, and that social stimuli would increase this response due to variations in vagal activity. Moreover, it was expected that physiological responses to social stimuli would be consistent across sessions. Contrary to expectations, there were no significant group or condition differences. Furthermore, the responses were less consistent than expected. These findings challenged the assumptions of persistent vagal dysregulation and chronic mobilization as proposed by the Polyvagal Theory. However, descriptive results aligned with theoretical expectations. Therefore, future research should build on the strengths of this study and address current limitations. Recommended directions include a larger sample size, more engaging or relevant social stimuli, and improved control of comorbidities, individual differences, and technical issues. This may reveal true differences or encourage the exploration of alternative explanations or theoretical refinement, to ultimately deepen our understanding of physiological arousal in individuals with autism.