title: Circadian patterns of sleep, sleepiness, and performance in older and younger adults.
abstract: OBJECTIVE
  To compare circadian patterns of sleep, subjective sleepiness, and psychomotor performance in older and younger adults.
  
  
  METHODS
  Controlled experimental laboratory study.
  
  
  METHODS
  General Clinical Research Center.
  
  
  METHODS
  Healthy older adults (n = 17, mean age 76 years) and healthy younger adults (n = 19, mean age 23 years).
  
  
  METHODS
  Subjects lived for 60 consecutive hours on a 90-minute sleep-wake cycle (30 minutes in bed, 60 minutes awake). Electroencephalographic recordings were conducted during bedrest periods. Self-ratings and psychomotor performance tests were conducted during 60-minute wake periods.
  
  
  RESULTS
  Data were analyzed with cosinor and linear mixed models. Amplitude and phase of the core body temperature rhythm did not significantly differ by age group. Older adults had significantly reduced mean levels and amplitude of rhythms in total sleep time and sleep efficiency and increased mean levels and amplitude of rhythms in sleep latency and wake after sleep onset. Age groups did not differ in mean level of subjective sleepiness, but older adults had reduced amplitude. Older adults had worse overall psychomotor performance, with evidence of larger circadian amplitude in some of these rhythms. Age groups did not differ on the phase position of any rhythm.
  
  
  CONCLUSIONS
  Older adults had a lower level and smaller circadian variation of sleep propensity compared with younger adults, whereas wakefulness and psychomotor performance rhythms tended to show increased circadian variation among older subjects. These findings likely result from a combination of age-related changes in cortical function, homeostatic sleep mechanisms, and circadian regulation.
authors.affiliation: Sleep and Chronobiology Program, University of Pittsburgh, PA, USA. buyssedj@upmc.edu
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Buysse
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Monk
authors.forename: Julie
authors.initials: J
authors.lastname: Carrier
authors.forename: Amy
authors.initials: A
authors.lastname: Begley
mesh_terms: D000328:Adult; D000368:Aged; D001831:Body Temperature; D006970:Disorders of Excessive Somnolence / Q000453:epidemiology*; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011596:Psychomotor Disorders / Q000175:diagnosis / Q000453:epidemiology; D020178:Sleep Disorders, Circadian Rhythm / Q000453:epidemiology*; D012895:Sleep, REM / Q000502:physiology