Abstract
OBJECTIVES: Bedtime procrastination (BP) is a significant contributor to insufficient sleep. While existing interventions primarily focus on behavioral aspects, BP involves complex interactions between behavioral, cognitive, and emotional components. This pilot study aimed to evaluate the effectiveness of Transdiagnostic Cognitive Behavioral Therapy in reducing bedtime procrastination by simultaneously targeting its behavioral, cognitive, and emotional dimensions. METHOD: In this double-blind randomized controlled trial, 32 university students with significant bedtime procrastination (BPS score ≥ 28) were randomly assigned to either a tCBT intervention (n = 16) or a wait-list control group (n = 16). The intervention consisted of 20 weekly one-hour sessions following the Unified Protocol. Outcomes were measured using the Bedtime Procrastination Scale (BPS), Sleep Beliefs Scale (SBS), and Difficulties in Emotion Regulation Scale (DERS) at pre-treatment, post-treatment, and 3-month follow-up. RESULTS: Mixed-model ANOVAs revealed significant time × group interactions for all outcome measures (p <.001). The intervention group showed substantial improvements in bedtime procrastination (η² = 0.404), emotion regulation (η² = 0.471), and sleep-related beliefs (η² = 0.404), with large effect sizes maintained at 3-month follow-up (Hedges' g = 1.29, 1.22, and 1.24 respectively). The wait-list group showed no significant changes. CONCLUSIONS: This study provides the first evidence for tCBT's effectiveness in treating bedtime procrastination through a comprehensive approach addressing multiple maintaining factors. The large effect sizes and maintenance of gains at follow-up suggest that targeting cognitive, behavioral, and emotional dimensions simultaneously may be more effective than single-component interventions. TRIAL REGISTRATION: This randomized clinical trial was registered in the Iranian Registry of Clinical Trials (IRCT Id: IRCT20200112046097N1). (Registration Date: 26/07/2020).