Sleep characteristics and cognitive impairment in the general population

OBJECTIVE: To assess the association between sleep structure and cognitive impairment in the general population. METHODS: Data stemmed from 580 participants aged >65 years of the population-based CoLaus/PsyCoLaus study (Lausanne, Switzerland) who underwent complete sleep evaluation (HypnoLaus). Evaluations included demographic characteristics, personal and treatment history, sleep complaints and habits (using validated questionnaires), and a complete polysomnography at home. Cognitive function was evaluated using a comprehensive neuropsychological test battery and a questionnaire on the participant's everyday activities. Participants with cognitive impairment (global Clinical Dementia Rating CDR scale score > 0) were compared with participants with no cognitive impairment (global CDR score = 0). RESULTS: The 291 participants with a CDR score > 0 (72.5 ± 4.6 years), compared to the 289 controls with CDR = 0 (72.1 ± 4.6 years), had significantly more light (stage N1) and less deep (stage N3) and REM sleep, as well as lower sleep efficiency, higher intrasleep wake, and higher sleepiness scores (all p 65 years with cognitive impairment have higher sleepiness scores and a more disrupted sleep. This seems to be related to the occurrence of sleep-disordered breathing and the associated intermittent hypoxia.