An interpretation of the internal desynchronizations based on dynamics of the two-process model

M. Nakao, H. Sakai, M. Yamamoto

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Daan's two-process model is known to be one of the most powerful models, covering various situations from free-running to sleep deprivation. In this study, bifurcation properties of the model dynamics are clarified using a circle map. In addition, the two-process model is applied to simulate the two distinct patterns (the period-prolonged: I and the period-shortened: II) of sleep-wake cycles during internal desynchronizations. We propose the novel interpretation that types I and II could be regarded as mutual entrainments between the body temperature rhythm and the sleep-wake cycle with the period ratios 3:4 and 3:2, respectively. From the bifurcation properties of the two- process model obtained above, the model is shown to be able to generate the respective type of mutual entrainment with an appropriate range of a parameter value, i.e, a gap between thresholds. The variable behavior of human circadian rhythm is suggested to be systematically understood based on the bifurcation properties of the two-process model.

Original languageEnglish
Pages (from-to)282-285
Number of pages4
JournalMethods of Information in Medicine
Issue number4-5
Publication statusPublished - 1997


  • Bifurcation
  • Desynchronization
  • Entrainment
  • Sleep-wake Cycle
  • Two-process Model

ASJC Scopus subject areas

  • Health Informatics
  • Advanced and Specialised Nursing
  • Health Information Management


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