The Impact of Working Night Shifts on Cardiac Autonomic Nervous Regulation During the Six-minute Walk Test in Nurses

Inclusion Criteria: * Female nurses aged ≥ 18 years who had undergone annual physical examinations, did not have serious cardiopulmonary diseases, and were able to walk normally were considered for inclusion in the study. Exclusion Criteria: * (ⅰ) having children at home who require night care; (ⅱ) current pregnancy; (ⅲ) engaging in activities that significantly impact heart rate, such as sexual activity, 24 hours before and 24 hours after working night shifts; (ⅳ) history of thyroid dysfunction, hypertension, diabetes, coronary heart disease, etc.; (ⅴ) experiencing upper respiratory tract infection, fever, cough, diarrhea, or other illnesses within 1 week before the planned enrollment; (ⅵ) consuming coffee or strong tea, smoking, drinking alcohol, or using other substances that affect heart rate 3 days before the planned enrollment; (ⅶ) taking β-receptor blockers, sleeping pills, psychotropic drugs, or other medications that affect heart rate; and (ⅷ) judged by the investigator to be unsuitable for participation in this study.