title: Sleep, Muscle Mass and Muscle Function in Older People.
abstract: BACKGROUND
  Loss of muscle mass, particularly in old age, can restrict mobility and physical function. Sleep is thought to play a key role in the maintenance of muscle mass; sleep disturbances have a prevalence of 6-30% in Germany. In this study, based on data from the Berlin Aging Study II (BASE-II), we analyze the relationship between sleep efficiency and quality on the one hand, and muscle mass and muscle function on the other.
  
  
  METHODS
  We analyzed cross-sectional data from 1196 subjects (52.5% women; 68 ± 4 years). Sleep behavior was assessed with questions from the Pittsburgh Sleep Quality Index; appendicular lean mass (ALM) with dual x-ray absorp - tiometry; and muscle function with a measure of grip strength and with questionnaires about physical activity and impairment of physical activities. Low muscle mass was determined from the ALM corrected by the body-mass index (BMI), i.e., from the ratio ALM/BMI.
  
  
  RESULTS
  19.1% of the women and 13.4% of the men reported poor sleep quality. Men whose ALM/BMI ratio was below the cutoff value for low muscle mass more frequently reported very poor sleep efficiency (9.1% , versus 4.8% in women; p<0.002). The adjusted odds ratio for low muscle mass was 2.8 for men with poor sleep quality (95% confidence interval: [1.1; 6.7]) and 4.3 for men with poor sleep efficiency [1.2; 15.1]. In women, there was no statistically significant association between sleep quality and efficiency on the one hand and ALM/BMI values below cutoff on the other, but poor sleep quality was found to be associated with reduced grip strength (16.25 kg ± 2.33 kg versus 15.67 kg ± 2.38 kg; p = 0.009) and low appendicular lean mass (ALM: 16.25 kg ± 2.33 kg versus 15.67 kg ± 2.38 kg; p = 0.016).
  
  
  CONCLUSIONS
  These findings support the hypothesis of a link between sleep and muscle mass. The dependence of muscle mass on sleep behavior needs to be investigated in longitudinal studies.
authors.affiliation: Geriatrics Research Group, Charité Universitätsmedizin, Berlin, Institute for Medical Genetics and Human Genetics, Charité Universitätsmedizin, Berlin, Rahel Eckardt and Elisabeth Steinhagen-Thiessen are joint last authors.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Buchmann
authors.forename: Dominik
authors.initials: D
authors.lastname: Spira
authors.forename: Kristina
authors.initials: K
authors.lastname: Norman
authors.forename: Ilja
authors.initials: I
authors.lastname: Demuth
authors.forename: Rahel
authors.initials: R
authors.lastname: Eckardt
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Steinhagen-Thiessen
mesh_terms: D000368:Aged; D015992:Body Mass Index; D015984:Causality; D015897:Comorbidity; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology*; D009135:Muscular Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D009929:Organ Size; D015995:Prevalence; D012307:Risk Factors; D017678:Sex Distribution; D012737:Sex Factors; D012890:Sleep; D012893:Sleep Wake Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*