ObjectiveTo capture any sleep quality changes associated with group psychotherapy. Patients/methods Physician-referred, chronically depressed patients (n = 25) were randomized to either eight group sessions of Mindfulness-based Cognitive Therapy (MBCT, n = 9) plus Treatment As Usual (TAU), or the Cognitive Behavioral Analysis System of Psychotherapy (CBASP, n = 8) plus TAU, or to TAU only (control group, n = 8). Participants recorded their sleep at home. The primary outcome variables were: stable and unstable sleep, which were assessed using cardiopulmonary coupling (CPC) analysis, and estimated total sleep and wake time (minutes). Cardiopulmonary coupling measures heart rate variability and the electrocardiogram's R-wave amplitude fluctuations associated with respiration. Results By post-treatment night 6, the CBASP group had more stable sleep (p = 0.044) and less wake (p = 0.004) compared with TAU, and less wake vs MBCT (p = 0.039). Conclusion The CBASP group psychotherapy treatment improved sleep quality compared with Treatment As Usual.