title: Associations of 24-hour sleep duration and CT-derived measurements of muscle and bone: The AGES-Reykjavik Study.
abstract: Although the importance of sleep on preservation of several physiological functions is well known, the relationship with the two interconnected tissues - muscle and bone is less understood.
  
  
  
  This study aimed to examine the association of 24-hour sleep duration with mid-thigh muscle composition and proximal femur volumetric bone mineral density (vBMD).
  
  
  
  2438 men and 3326 women aged 66 to 96years, residents in the Reykjavik area, were included in this cross-sectional study. Proximal femur integral vBMD, mid-thigh muscle area and muscle attenuation were assessed with computed tomography. Sleep and nap habits were assessed using a questionnaire.
  
  
  
  We found that after adjustment for age and BMI long sleep duration (>8h/d) was negatively associated with thigh lean area in both men (B=-2.21, 95% confidence interval (CI): -4.01, -0.40) and women (B=-2.39, 95% CI: -3.75, -1.03) and with muscle attenuation (B=-0.95, 95% CI: -1.47, -0.43) only in women. After adjustments for age, health and lifestyle factors the association between long sleep duration and muscle lean area was attenuated and became nonsignificant while associations with muscle attenuation remained marginally significant (B=-0.51, 95% CI: -1.03, -0.002). Sleep duration was not associated with proximal femur integral vBMD in the multivariate models.
  
  
  
  Long sleep duration, particularly in old women, can affect thigh muscle attenuation (increase in intramuscular fat). Whether optimization of sleep can ameliorate age-associated intramuscular or intermuscular adipose tissue warrants further studies.
authors.affiliation: Laboratory of Epidemiology and Population Sciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Bethesda, 7201 Wisconsin Avenue, Gateway Building, Suite 2N300, Bethesda, MD 20892-9205, USA. Electronic address: elisa.marques@nih.gov.
authors.forename: Elisa A
authors.initials: EA
authors.lastname: Marques
authors.affiliation: Laboratory of Epidemiology and Population Sciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Bethesda, 7201 Wisconsin Avenue, Gateway Building, Suite 2N300, Bethesda, MD 20892-9205, USA; Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University Institute of Maia, ISMAI, Av. Carlos Oliveira Campos, Castelo da Maia 4475-690, Maia, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Figueiredo
authors.affiliation: Icelandic Heart Association Research Institute, Kópavogur, Holtasmari 1, IS-201 Kópavogur, Iceland; University of Iceland, Reykjavik, Sæmundargata 2, 101 Reykjavík Ssn: 600169-2039, Iceland.
authors.forename: Vilmundur
authors.initials: V
authors.lastname: Gudnason
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, 505 Parnassus Ave, San Francisco, CA 94143, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lang
authors.affiliation: Icelandic Heart Association Research Institute, Kópavogur, Holtasmari 1, IS-201 Kópavogur, Iceland; University of Iceland, Reykjavik, Sæmundargata 2, 101 Reykjavík Ssn: 600169-2039, Iceland; Landspitali-University Hospital, 101 Reykjavik, Iceland.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Sigurdsson
authors.affiliation: Icelandic Heart Association Research Institute, Kópavogur, Holtasmari 1, IS-201 Kópavogur, Iceland.
authors.forename: Sigurdur
authors.initials: S
authors.lastname: Sigurdsson
authors.affiliation: Icelandic Heart Association Research Institute, Kópavogur, Holtasmari 1, IS-201 Kópavogur, Iceland; Centre of Public Health Sciences, University of Iceland, Stapi v. Hringbraut, 107 Reykjavík, Iceland.
authors.forename: Thor
authors.initials: T
authors.lastname: Aspelund
authors.affiliation: Icelandic Heart Association Research Institute, Kópavogur, Holtasmari 1, IS-201 Kópavogur, Iceland.
authors.forename: Kristin
authors.initials: K
authors.lastname: Siggeirsdottir
authors.affiliation: Laboratory of Epidemiology and Population Sciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Bethesda, 7201 Wisconsin Avenue, Gateway Building, Suite 2N300, Bethesda, MD 20892-9205, USA.
authors.forename: Lenore
authors.initials: L
authors.lastname: Launer
authors.affiliation: Icelandic Heart Association Research Institute, Kópavogur, Holtasmari 1, IS-201 Kópavogur, Iceland.
authors.forename: Gudny
authors.initials: G
authors.lastname: Eiriksdottir
authors.affiliation: Laboratory of Epidemiology and Population Sciences, Intramural Research Program, National Institute on Aging, National Institutes of Health, Bethesda, 7201 Wisconsin Avenue, Gateway Building, Suite 2N300, Bethesda, MD 20892-9205, USA.
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D012890:Sleep / Q000502:physiology*; D013848:Thigh / Q000033:anatomy & histology; D013997:Time Factors; D014057:Tomography, X-Ray Computed
keywords: Computed tomography; Fat infiltration; Muscle composition; Proximal femur