Effect of Daylight Duration on Outcomes of Repetitive Transcranial Magnetic Stimulation in Treatment-Resistant Depression

To examine the possible impact of daylight duration on the efficacy of repetitive transcranial magnetic stimulation (rTMS) in patients with treatment-resistant depression (TRD). A retrospective cohort study of 151 patients with TRD undergoing rTMS was conducted. The patient data were collected over multiple years from August 2018 to August 2025. Depression severity was assessed using the Patient Health Questionnaire-9 (PHQ-9) and Hamilton Depression Rating Scale (HDRS) before and after treatment. Patients were categorized into 3 groups: responders, remitters, and nonresponders. Responders were defined by a decrease in PHQ-9 or HDRS score by 50% or more. Remitters were defined by achieving a PHQ-9 score