Six-Week Multimodal Smartphone Restriction for Sleep, Autonomic Regulation, Cognition and Physical Performance in Physically Active University Students with Nomophobia

INTERVENTION: Multimodal Smartphone Restriction Smartphone Restriction and Psychoeducation Usual Habits Control CONDITION: ; Physical Activity and Health Physical Activity and Health PRIMARY OUTCOME: Sleep efficiency (SE), measured by wrist actigraphy (ActiGraph wGT3X‐BT), expressed as the percentage of time asleep relative to time spent in bed. SECONDARY OUTCOME: Total sleep time (TST), sleep onset latency (SOL), and wake after sleep onset (WASO), measured by wrist actigraphy (ActiGraph wGT3X‐BT). INCLUSION CRITERIA: 1. Age range: 19 to 24 years 2. Regular physical activity: at least three sessions per week for more than one year. 3. Moderate‐to‐severe nomophobia confirmed using the NMP‐Q. 4. Intermediate chronotype on the Morningness‐Eveningness Questionnaire (MEQ score 42–58). 5. Smartphone capable of exporting native usage metrics (e.g., Screen Time or Digital Wellbeing).