title: Effects of sleep fragmentation on the arousability to resistive loading in NREM and REM sleep in normal men.
abstract: OBJECTIVE
  In healthy subjects, arousability to inspiratory resistive loading is greater during rapid eye movement (REM) sleep compared with non-REM (NREM) sleep but is poorest in REM sleep in patients with sleep apnea. We therefore examined the hypothesis that sleep fragmentation impairs arousability, especially from REM sleep.
  
  
  METHODS
  Two blocks of 3 polysomnographies (separated by at least 1 week) were performed randomly. An inspiratory-loaded night followed either 2 undisturbed control nights (LN(C)) or 2 acoustically fragmented nights (LN(F)) SETTING: Sleep laboratory.
  
  
  METHODS
  Sixteen healthy men aged 20 to 29 years.
  
  
  METHODS
  In both loaded nights, an inspiratory resistive load was added via a valved facemask every 2 minutes during sleep and turned off either when arousal occurred or after 2 minutes.
  
  
  RESULTS
  During LN(F), arousability remained significantly greater in REM sleep (71% aroused within 2 minutes) compared with stage 2 (29%) or stage 3/4 (16%) sleep. After sleep fragmentation, arousability was decreased in stage 2 sleep (LN(F): 29%; LN(C): 38%; p < .05) and low in early REM sleep, increasing across the night (p < .01). In stage 3/4 sleep, neither an attenuation nor a change across the night was seen after sleep fragmentation.
  
  
  CONCLUSIONS
  Mild sleep fragmentation is already sufficient to attenuate arousability in stage 2 sleep and to decrease arousability in early, compared with late, REM sleep. This means that sleep fragmentation affects the arousal response to increasing resistance and that the effects are different in stage 2 and REM sleep. The biologic reason for this increase in the arousal response in REM sleep across the night is not clear.
authors: Sleep Medicine Center, Inselspital, University of Berne, Berne, Switzerland.
authors: Jeannette
authors: J
authors: Zavodny
authors: Corinne
authors: C
authors: Roth
authors: Claudio L
authors: CL
authors: Bassetti
authors: Johannes
authors: J
authors: Mathis
authors: Neil J
authors: NJ
authors: Douglas
authors: Matthias
authors: M
authors: Gugger