Impact of physical activity on sleep in adults recovering from substance use disorders: a protocol for an N-of-1 observational study.

INTRODUCTION: Sleep impairments are prevalent among individuals recovering from substance use disorders (SUDs) and are associated with poorer treatment outcomes and increased relapse risk. Physical activity (PA) is known to enhance sleep in general populations, but its day-to-day effects on sleep during SUD recovery remain underexplored, especially across different recovery stages. METHODS AND ANALYSIS: In this observational n-of-1 study, we aim to examine within-person associations between daily PA and sleep quality in three groups of individuals at varying stages of substance use recovery (early treatment, continuing care and long-term recovery). A substudy will validate the agreement between two wearable sleep-monitoring devices. A total of 90 participants (30 per recovery group) from Western Australia will complete daily ecological momentary assessments and wear the SENS Motion sensor and/or Withings Sleep Analyzer over a 30-day period. Outcomes include device-derived sleep and PA measures, self-reported affect, craving, well-being and recovery outcomes. Multilevel models will explore within-person and between-person associations. This study will generate individualised evidence on associations between PA and sleep to inform tailored SUD care. It will also assess the feasibility of using wearable sleep monitors in real-world SUD recovery settings. Results may support the future development of just-in-time adaptive intervention procedures. ETHICS AND DISSEMINATION: The study was approved by the Human Research Ethics Committee of Curtin University (HRE2025-0379). Findings will be shared through peer-reviewed publications and conference presentations, with lay summaries provided to treatment facilities and interested participants to support translation into community and service settings. TRIAL REGISTRATION NUMBER: ACTRN12625000835448.