Subsequently, we excluded the following patients: 11 patients with RCSQ scores of 25–75, eight patients with two inconsistent sleep assessment, six patients with length of ICU stay <48 h after inclusion, three patients with alcohol abuse or mental illness, three patients with chronic renal failure, three patients with clinical and laboratory data missing, two patients with BNP >2,000 pg/ml, two patients who received deep sedation, one patient with acute myocardial infarction, one patient with chronic insomnia, one patient with acute monocytic leukemia, and one patient with granulocytopenia. Here, NPPB is linked to acute myocardial infarction.