Patients with deterioration of their health condition requiring ICU care, or those with a duration of hospital stay < 21 days were assigned to one of the two groups based on the overall quality of their sleep within the first two weeks after hospital admission: patients with two RCSQ scores ≥ 70 and PSQI ≤ 7 were assigned to the good-sleep group and those with one RCSQ score ≤ 50 and PSQI > 7 were assigned to the poor-sleep group.