This clinical trial tests whether combining regular play therapy with gamified biofeedback helps children with autism spectrum disorder better regulate their emotions and improve social skills, compared to play therapy alone. Sixty-eight children will be randomly assigned to 8 weekly 50-minute sessions: one group receives play therapy only, while the other receives play therapy plus real-time biofeedback using a comfortable armband that turns heart-rate calming into fun game rewards. Parents and teachers will complete short questionnaires before and after the study. All activities are playful, safe, and designed to feel natural and enjoyable for children with autism.

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by persistent difficulties in social communication and interaction, restricted interests, and repetitive behaviors. Even in children with ASD level 1 (requiring support) who have normal or high cognitive abilities, emotional dysregulation is one of the most significant and persistent challenges. These children frequently experience intense physiological arousal in response to everyday sensory or social stimuli, yet they struggle to recognize, interpret, and self-regulate their emotional states. Traditional behavioral and developmental therapies improve communication and reduce repetitive behaviors, but emotional dysregulation often remains a major barrier to social participation, learning, and family well-being, contributing to frequent anxiety, and long-term mental health risks.

This single-center, pragmatic, parallel-group, single-blind (outcome assessor) randomized clinical trial aims to determine whether integrating real-time gamified biofeedback with standard child-centered play therapy produces greater improvements in emotional regulation and socioemotional skills than play therapy alone in children aged 6-10 years diagnosed with ASD level 1 according to DSM-5 criteria.

A total of 68 children will be consecutively recruited from the outpatient clinic of the Faculdade de Ciências Médicas de Minas Gerais (FCMMG), Belo Horizonte, Brazil. After obtaining written informed consent from parents/legal guardians and child assent, participants will be randomly allocated in a 1:1 ratio (using computer-generated randomization) to one of two interventions delivered over 12 weeks in weekly 50-minute individual sessions conducted by the same psychologist experienced in autism spectrum disorder.

Both groups receive identical child-centered play therapy focused on fostering joint attention, symbolic play, reciprocal interaction, and emotional co-regulation in a sensory-friendly room adapted for children with autism. The experimental group additionally receives gamified biofeedback (heart-rate monitor armband that adjusts game difficulty based on arousal level, rewarding successful calming strategies) and continuous physiological monitoring with the a FDA-cleared research device recording heart-rate variability, electrodermal activity, peripheral skin temperature, accelerometry, and respiratory rate). The control group plays the same tablet games but with the biofeedback function deactivated (sham condition).

Blinded assessments are conducted at baseline and immediately after the intervention. The primary outcome is the change in emotion regulation scores. Secondary outcomes include changes in sociability, behavior, parenting stress, and exploratory correlations between physiological biomarkers and clinical improvements. The study follows CONSORT guidelines and has been approved by the institutional ethics committee (CEP-FCMMG).

Inclusion Criteria:

• Age between 6 years and 10 years
• Formal diagnosis of autism spectrum disorder (ASD) level 1 according to DSM-5 criteria, documented by a qualified professional
• Signed informed consent by parent/legal guardian and child assent

Exclusion Criteria:

• Severe psychiatric comorbidities (e.g., psychosis, severe obsessive-compulsive disorder)
• Uncontrolled epilepsy or contraindication to biofeedback procedures
• Severe intellectual disability that prevents interaction with tablet-based games or biofeedback
• Severe or decompensated systemic medical conditions (e.g., active cancer, uncontrolled cardiac disease, uncontrolled diabetes)
• Change in dose or initiation of any psychotropic medication within 4 weeks prior to enrollment

De-identified individual participant data (including data dictionaries) that underlie the results reported in the primary publication (including the primary and secondary outcome measures, baseline characteristics, and adverse events) will be made available upon reasonable request beginning 6 months and ending 5 years following article publication. Data will be shared with researchers who provide a methodologically sound proposal and have appropriate ethical approval. Requests should be directed to the Principal Investigator.

6 months after publication - 5 years after publication

Researchers must submit a brief research proposal and sign a data access agreement. Data will be shared via secure file transfer after approval by the Principal Investigator.