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Adjusted mean change in Trails B completion time by quartile of percent of sleep time spent in Stage N1. Adjusted by age, site, race (white versus nonwhite), education, depression, history of hypertension, history of angina, history of myocardial infarction, history of congestive heart failure, history of stroke/transient ischemic attack, benzodiazepine use, antidepressant use, self-reported health status, physical activity, and smoking status.
