Adjunctive bright light therapy to enhance continuous positive airway pressure adherence in patients with comorbid major depressive disorder and obstructive sleep apnoea syndrome: study protocol for a randomised sham-controlled trial.

introductionObstructive sleep apnoea syndrome (OSAS) co-occurs with major depressive disorder (MDD) in approximately 50% of cases, and this comorbidity is associated with greater severity of depressive symptoms, sleep disturbances and poorer clinical outcomes. Although continuous positive airway pressure (CPAP) therapy is effective in treating OSAS and alleviating symptoms of MDD, poor adherence during the initial weeks of treatment remains a major clinical challenge. Bright light therapy has been shown to rapidly improve sleep, wakefulness, cognitive function and mood in patients with MDD. Given these complementary mechanisms, we propose that combining CPAP with bright light therapy may enhance patient adherence during the critical initial phase of CPAP treatment, ultimately leading to better clinical and sleep-related outcomes. METHODS AND ANALYSIS: In a single-centre, double-blind, sham-controlled study with two parallel arms, 130 patients with both MDD and OSAS requiring CPAP therapy will be randomly assigned to receive either 14 sessions of 30 min active bright light therapy (n=65, 1200 Lux, peak wavelength at 500 nm) or 14 sessions of 30 min sham bright light therapy (n=65, 33 Lux, peak wavelength at 600 nm) during the first 2 weeks, following CPAP initiation at home. The primary outcome will be adherence to CPAP (in hours per 24 hours during the 14 days of investigation). Secondary clinical outcomes will include changes in depressive and anxiety symptoms. Secondary sleep-related outcomes will include both objective sleep parameters (polysomnography, melatonin and actimetry) and standardised psychometric scales. The persistence of treatment effects at 1-month follow-up will also be evaluated. ETHICS AND DISSEMINATION: The study was approved by an ethics committee (CPP Nord Ouest IV, Lille, France), and the French National Agency for Medicines and Health Products Safety registration number 2024-A01551-46. The findings will be disseminated through international peer-reviewed publications, presentations at scientific conferences and outreach at public conferences. TRIAL REGISTRATION NUMBER: NCT06781593.