Inclusion Criteria:  age of 20 to 75 years old diagnosis of COPD made by pulmonologist (Kuo YL) if the patient had a long-term smoking or noxious gas exposure history, typical clinical manifestations, and airflow limitation with a postbronchodilator FEV1/FVC ratio of < 0.7 in spirometry,4 and provision of written informed consent.  Exclusion Criteria:  severe and unstable comorbidities or active malignancy history of obstructive sleep apnoea syndrome COPD exacerbation within the 4 weeks prior current use of long-term oxygen therapy or noninvasive ventilation or use within the 6 weeks prior cognitive impairment or a psychiatric disorder pregnancy