title: NREM sleep stage transitions control ultradian REM sleep rhythm.
abstract: OBJECTIVE
  The cyclic sequence of NREM and REM sleep, the so-called ultradian rhythm, is a highly characteristic feature of sleep. However, the mechanisms responsible for the ultradian REM sleep rhythm, particularly in humans, have not to date been fully elucidated. We hypothesize that a stage transition mechanism is involved in the determination of the ultradian REM sleep rhythm.
  
  
  METHODS
  Ten healthy young male volunteers (AGE: 22 ± 4 years, range 19-31 years) spent 3 nights in a sleep laboratory. The first was the adaptation night, and the second was the baseline night. On the third night, the subjects received risperidone (1 mg tablet), a central serotonergic and dopaminergic antagonist, 30 min before the polysomnography recording.
  
  
  RESULTS
  We measured and investigated transition probabilities between waking, REM, and NREM sleep stages (N1, N2, and N3) within the REM-onset intervals, defined as the intervals between the onset of one REM period and the beginning of the next, altered by risperidone. We also calculated the transition intensity (i.e., instantaneous transition rate) and examined the temporal pattern of transitions within the altered REM-onset intervals. We found that when the REM-onset interval was prolonged by risperidone, the probability of transitions from N2 to N3 was significantly increased within the same prolonged interval, with a significant delay and/or recurrences of the peak intensity of transitions from N2 to N3.
  
  
  CONCLUSIONS
  These results suggest that the mechanism governing NREM sleep stage transitions (from light to deep sleep) plays an important role in determining ultradian REM sleep rhythms.
authors.affiliation: Educational Physiology Laboratory, Graduate School of Education, The University of Tokyo, Tokyo, Japan.
authors.forename: Akifumi
authors.initials: A
authors.lastname: Kishi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yasuda
authors.forename: Takahisa
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Inami
authors.forename: Jun
authors.initials: J
authors.lastname: Horiguchi
authors.forename: Masako
authors.initials: M
authors.lastname: Tamaki
authors.forename: Zbigniew R
authors.initials: ZR
authors.lastname: Struzik
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Yamamoto
mesh_terms: D000328:Adult; D018492:Dopamine Antagonists / Q000494:pharmacology; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D006801:Humans; D008297:Male; D017286:Polysomnography; D018967:Risperidone / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology*; D055815:Young Adult
chemical_list: D018492:Dopamine Antagonists; D012702:Serotonin Antagonists; D018967:Risperidone