title: Aging effects on cardiac and respiratory dynamics in healthy subjects across sleep stages.
abstract: OBJECTIVE
  Respiratory and heart rate variability exhibit fractal scaling behavior on certain time scales. We studied the short-term and long-term correlation properties of heartbeat and breathing-interval data from disease-free subjects focusing on the age-dependent fractal organization. We also studied differences across sleep stages and night-time wake and investigated quasi-periodic variations associated with cardiac risk.
  
  
  METHODS
  Full-night polysomnograms were recorded during 2 nights, including electrocardiogram and oronasal airflow.
  
  
  METHODS
  Data were collected in 7 laboratories in 5 European countries.
  
  
  METHODS
  180 subjects without health complaints (85 males, 95 females) aged from 20 to 89 years.
  
  
  METHODS
  None.
  
  
  RESULTS
  Short-term correlations in heartbeat intervals measured by the detrended fluctuation analysis (DFA) exponent alpha1 show characteristic age dependence with a maximum around 50-60 years disregarding the dependence on sleep and wake states. Long-term correlations measured by alpha2 differ in NREM sleep when compared with REM sleep and wake, besides weak age dependence. Results for respiratory intervals are similar to those for alpha2 of heartbeat intervals. Deceleration capacity (DC) decreases with age; it is lower during REM and deep sleep (compared with light sleep and wake).
  
  
  CONCLUSIONS
  The age dependence of alpha1 should be considered when using this value for diagnostic purposes in post-infarction patients. Pronounced long-term correlations (larger alpha2) for heartbeat and respiration during REM sleep and wake indicate an enhanced control of higher brain regions, which is absent during NREM sleep. Reduced DC possibly indicates an increased cardiovascular risk with aging and during REM and deep sleep.
authors.affiliation: Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany.
authors.forename: Aicko Y
authors.initials: AY
authors.lastname: Schumann
authors.forename: Ronny P
authors.initials: RP
authors.lastname: Bartsch
authors.forename: Thomas
authors.initials: T
authors.lastname: Penzel
authors.forename: Plamen Ch
authors.initials: PCh
authors.lastname: Ivanov
authors.forename: Jan W
authors.initials: JW
authors.lastname: Kantelhardt
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods; D012016:Reference Values; D012119:Respiration; D012894:Sleep Stages / Q000502:physiology*; D055815:Young Adult