“…Several within-patient studies have investigated the effects of CPAP on leptin levels by comparing baseline to post-treatment values, with 12 reporting significant reductions in leptin after treatment [7, 9, 10, 32, 33, 50–56] and six reporting no change [17, 18, 48, 57–59]. In most cases, leptin was sampled in the morning after an overnight fast [7, 9, 10, 17, 18, 32, 33, 48, 50–52, 55–59], and in one case, which did report post-treatment reductions, it was sampled throughout the night [53]. The duration of treatment from baseline to follow-up ranged from 1 day to 6 months, and does not seem to contribute to disparate findings.…”