Nocturnal sleep duration and cognitive impairment in a population-based study of older adults

Objective We aimed to investigate the association between nocturnal sleep duration, changes in nocturnal sleep duration and cognitive impairment in older adults. Methods 4010 participants of a population-based cohort study provided information on nocturnal sleep duration at baseline (1991–1995) and at follow-up (2002/2003). 792 follow-up participants aged 70+ by 2006 participated in telephone-based cognitive assessments. Several cognitive tests were used including the telephone interview for cognitive status (TICS). Cognitive impairment was defined as <31 points on the TICS (13.0%) and as below this percentile on the other tests. Based on individual tests, a verbal memory score and a total …