Sleep characteristics and cognitive impairment in the general population: The HypnoLaus study

Neurology. 2017 Jan 31;88(5):463-469. doi: 10.1212/WNL.0000000000003557. Epub 2016 Dec 30.


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 < 0.05). Sleep-disordered breathing was more severe in participants with cognitive impairment with an apnea/hypopnea index (AHI) of 18.0 (7.8-35.5)/h (p50 [p25-p75]) (vs 12.9 [7.2-24.5]/h, p < 0.001), and higher oxygen desaturation index (ODI). In the multivariate analysis after adjustments for confounding variables, the AHI and the ODI ≥4% and ≥6% were independently associated with cognitive impairment.

Conclusions: Participants aged >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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Cognitive Dysfunction / complications
  • Cognitive Dysfunction / physiopathology*
  • Follow-Up Studies
  • Humans
  • Mental Status Schedule
  • Multivariate Analysis
  • Neuropsychological Tests
  • Polysomnography
  • Severity of Illness Index
  • Sleep Wake Disorders / complications
  • Sleep Wake Disorders / physiopathology
  • Sleep Wake Disorders / psychology
  • Sleep* / physiology
  • Surveys and Questionnaires
  • Switzerland