Zeitgeber hierarchy in humans: Resetting the circadian phase positions of blind people using melatonin

Alfred J. Lewy, Jonathan Emens, Robert L. Sack, Brant P. Hasler, Rebecca A. Bernert

Research output: Contribution to journalArticle

31 Scopus citations


Four blind individuals who were thought to be entrained at an abnormal circadian phase position were reset to a more normal phase using exogenous melatonin administration. In one instance, circadian phase was shifted later. A fifth subject who was thought to be entrained was monitored over four years and eventually was shown to have a circadian period different from 24h. These findings have implications for treating circadian phase abnormalities in the blind, for distinguishing between abnormally entrained and free-running blind individuals, and for informing the debate over zeitgeber hierarchy in humans.

Original languageEnglish (US)
Pages (from-to)837-852
Number of pages16
JournalChronobiology International
Issue number5
StatePublished - Oct 9 2003



  • Circadian rhythms
  • Entrainment
  • Melatonin
  • Melatonin phase response curve
  • Totally blind people

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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