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

Chronobiol Int. 2003 Sep;20(5):837-52. doi: 10.1081/cbi-120024215.


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 24 h. 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.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Blindness / physiopathology*
  • Circadian Rhythm / drug effects*
  • Circadian Rhythm / physiology
  • Female
  • Humans
  • Male
  • Melatonin / administration & dosage*
  • Melatonin / physiology
  • Middle Aged
  • Models, Biological


  • Melatonin