title: Subjective sleep quality and daytime sleepiness in late midlife and their association with age-related changes in cognition.
abstract: In an increasingly aged population, sleep disturbances and neurodegenerative disorders have become a major public health concern. Poor sleep quality and cognitive changes are complex health problems in aging populations that are likely to be associated with increased frailty, morbidity, and mortality, and to be potential risk factors for further cognitive impairment. We aimed to evaluate whether sleep quality and excessive daytime sleepiness may be considered as early predictors of cognitive impairment.
  
  
  OBJECTIVE
  The objective of this study was to examine whether subjective sleep quality and daytime sleepiness are associated with cognition in middle-aged males.
  
  
  METHODS
  A total of 189 healthy males born in 1953 were considered as participants for the study. Based on previous cognitive assessments, the participants were selected for the study as cognitively improved (N = 97) or cognitively impaired (N = 92).
  
  
  METHODS
  The Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale measured subjective sleep quality and daytime sleepiness, respectively. Depressive symptoms were determined using Beck's Depression Inventory (BDI-II). A neuropsychological battery was administered to confirm group differences in cognitive functioning at the time when sleep data were collected.
  
  
  RESULTS
  Compared with cognitively improved males, the cognitively impaired group reported significantly lower subjective sleep quality (5.40 ± 3.81 vs. 4.39 ± 2.40, p = 0.03). Forty-one percent of the sample exhibited poor sleep quality and 15% experienced excessive daytime sleepiness. There were few correlations between sleep parameters and cognitive test performance in the combined sample.
  
  
  CONCLUSIONS
  Self-reported poor sleep quality was related to cognitive changes, whereas daytime sleepiness was not related. Our results suggest that sleep quality may be an early marker of cognitive decline in midlife.
authors.affiliation: Department of Clinical Neurophysiology, Danish Center for Sleep Medicine, Glostrup Hospital, Glostrup, Copenhagen, Denmark; Faculty of Health Science, Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark. Electronic address: katja.linda.waller.01@regionh.dk.
authors.forename: Katja Linda
authors.initials: KL
authors.lastname: Waller
authors.affiliation: Faculty of Health Science, Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark; Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Erik Lykke
authors.initials: EL
authors.lastname: Mortensen
authors.affiliation: Faculty of Health Science, Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark; Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Avlund
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark; Research Center for Prevention and Health, Glostrup Hospital, Glostrup, Copenhagen, Denmark.
authors.forename: Merete
authors.initials: M
authors.lastname: Osler
authors.affiliation: Center for Neuropsychiatric Schizophrenia Research and Lundbeck Foundation Centre for Clinical Intervention and Neuropsychiatric Schizophrenia Research, University of Copenhagen, Psychiatric Centre Glostrup, Glostrup, Copenhagen, Denmark.
authors.forename: Birgitte
authors.initials: B
authors.lastname: Fagerlund
authors.affiliation: Faculty of Health Science, Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Neurophysiology, Glostrup Hospital, Glostrup, Copenhagen, Denmark.
authors.forename: Martin
authors.initials: M
authors.lastname: Lauritzen
authors.affiliation: Department of Clinical Neurophysiology, Danish Center for Sleep Medicine, Glostrup Hospital, Glostrup, Copenhagen, Denmark; Faculty of Health Science, Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Poul
authors.initials: P
authors.lastname: Jennum
mesh_terms: D000367:Age Factors; D060825:Cognitive Dysfunction / Q000150:complications* / Q000175:diagnosis; D003863:Depression / Q000175:diagnosis*; D006970:Disorders of Excessive Somnolence / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D057566:Self Report; D012893:Sleep Wake Disorders / Q000175:diagnosis / Q000209:etiology*; D011795:Surveys and Questionnaires
keywords: Cognition; Cognitive decline; Elderly people; Sleep quality