The concept of habituation has been widely used in several domains, ranging from neuroscience of learning and memory to sensory profiling as well as neurological and neurodevelopmental disorders characterization. Defined as the ability of the nervous system to reduce its response over repeated stimulation, habituation inflects its parameters in terms of frequency, intensity, recovery and anticipation of responses. Historically, this concepts has developed from the study of the Central Nervous System (CNS) as being designated in processing stimuli at the cortical level. In this work, we aim at defining habituation from the point of view of the peripheral autonomic nervous system (ANS) via heart rate and heart rate variability assessments. In particular, we devise a reactivity function describing the time-varying ANS response with a point-process approach. The point process paradigm allows to extract parameters of autonomic responses which can be analyzed in terms of intensity and anticipation, whose reduction (or increment) over repeated stimuli can be ascribed to habituating (or sensitizating) patterns. We tested the mathematical formalization of such metrics in both neurotypical subjects and children with autism spectrum disorder (ASD). By eliciting autonomic responses via audio-video naturalistic stimulation, we collected electrocardiography (ECG), extracted the R waves, computed a reactivity function from a point process model of heart rate dynamics, and performed the Person’s coefficient between autonomic habituation metrics and participants’ sensory profiles and disorder severeness. Results show a relevant positive correlation with the Short Sensory Profile (SSP-2) questionnaire (60%) and with the Autism Diagnostic Observation Schedule (ADOS-2) questionnaire (76%).