title: Self-reported sleep duration and time in bed as predictors of physical function decline: results from the InCHIANTI study.
abstract: OBJECTIVE
  To characterize elderly persons into sleep/rest groups based on their self-reported habitual total sleeping time (TST) and habitual time in bed (TIB) and to examine the prospective association between sleep/rest behavior on physical function decline.
  
  
  METHODS
  Population-based InCHIANTI study with 6 years follow-up (Tuscany, Italy).
  
  
  METHODS
  Community.
  
  
  METHODS
  Men and women aged ≥ 65 years (n = 751).
  
  
  RESULTS
  At baseline, participants were categorized into 5 sleep/rest behavior groups according to their self-reported TST and TIB, computed from bedtime and wake-up time. Physical function was assessed at baseline and at 3- and 6-year follow-ups as walking speed, the Short Physical Performance Battery (SPPB), and self-reported mobility disability (ability to walk 400 m or climb one flight of stairs). Both long (≥ 9 h) TST and long TIB predicted accelerated decline in objectively measured physical performance and greater incidence in subjectively assessed mobility disability, but short (≤ 6 h) TST did not. After combining TST and TIB, long sleepers (TST and TIB ≥ 9 h) experienced the greatest decline in physical performance and had the highest risk for incident mobility disability in comparison to mid-range sleepers with 7-8 h TST and TIB. Subjective short sleepers reporting short (≤ 6 h) TST but long (≥ 9 h) TIB showed a greater decline in SPPB score and had a higher risk of incident mobility disability than true short sleepers with short (≤ 6 h) TST and TIB ≤ 8 hours.
  
  
  CONCLUSIONS
  Extended time in bed as well as long total sleeping time is associated with greater physical function decline than mid-range or short sleep. TIB offers important additive information to the self-reported sleep duration when evaluating the consequences of sleep duration on health and functional status.
authors: National Institute for Health and Welfare, Department of Health, Functional Capacity and Welfare, Functional Capacity Unit, Turku, Finland. sari.stenholm@thl.fi
authors: Sari
authors: S
authors: Stenholm
authors: Erkki
authors: E
authors: Kronholm
authors: Stefania
authors: S
authors: Bandinelli
authors: Jack M
authors: JM
authors: Guralnik
authors: Luigi
authors: L
authors: Ferrucci
mesh_terms: D000203:Activities of Daily Living / Q000523:psychology; D000368:Aged; D002097:C-Reactive Protein / Q000032:analysis; D005260:Female; D006304:Health Status; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D010809:Physical Fitness / Q000502:physiology / Q000523:psychology; D012146:Rest / Q000502:physiology* / Q000523:psychology; D012890:Sleep / Q000502:physiology*; D012892:Sleep Deprivation / Q000150:complications* / Q000503:physiopathology / Q000523:psychology; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein