Alterations in level, timing, and coupling of circadian excretion of catecholamine metabolites, adrenal cortical hormones, sodium, potassium, creatinine, and vital signs in acute-care surgical patients were measured. Data were examined to determine if a relationship exists between the degree of circadian alteration and the subject's reentrainment to typical circadian profiles.Urine samples for assay, temperature, heart rate, and blood pressure were collected daily at 2-hour intervals from 11 consenting surgery subjects and 10 age-and sex-matched control subjects.The data indicate that certain circadian rhythms of hospitalized subjects were altered and uncoupled from external stimuli. These findings suggest that nurses (1) give individualized patient care to promote reentrainment recovery; and (2) refine nursing assessment to consider individual circadian patterns.