['The purpose of this study is to explore the effect of a moderate dose of alcohol on sleep architecture and respiration in chronic obstructive pulmonary disease (COPD). Alcohol depresses both hypercapnic and hypoxic ventilatory drives in awake, normal individuals and reduces the amount of rapid eye movement (REM) sleep and oxygen saturation (SpO2) in sleeping COPD subjects.', 'Prospectively designed, open-label interventional study in a pulmonary rehabilitation hospital. Twenty-six (nine males) stable inpatients, median forced expiratory volume first second (FEV1) 40.5\xa0% of predicted, median age 65\xa0years, investigated by polysomnography including transcutaneous measurement of carbon dioxide pressure increase (ΔPtcCO2) in randomized order of either control sleep or intervention with 0.5\xa0g of ethanol/kilogram bodyweight, taken orally immediately before lights off.', 'Alcohol induced a mean increase (95\xa0% confidence interval, [CI]) in the mean ΔPtcCO2 of 0.10\xa0kPa (0.002-0.206, P\u2009=\u20090.047) and a mean decrease (CI) in the REM-sleep percentage of total sleep time (REM % of TST) of 3.1\xa0% (0.2-6.0), (P\u2009=\u20090.020). Six subjects with apnea/hypopnea index (AHI) ≥15 had fewer apneas/hypopneas during alcohol versus control sleep (mean reduction of AHI 11 (1-20), P\u2009=\u20090.046). Alcohol-sleep changes in SpO2, but not in ΔPtcCO2, correlated with daytime arterial pressures of carbon dioxide (PaCO2) and oxygen (PaO2).'] Does alcohol at bedtime induce minor changes in sleep stages and blood gases in stable chronic obstructive pulmonary disease?