Morningness and eveningness: The free cortisol rise after awakening in “early birds” and “night owls”

Oct 21, 2005Biological psychology

Morning and evening types show different rises in cortisol after waking

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Abstract

In a sample of 112 healthy, day-active young men, morning chronotypes exhibited higher cortisol levels in the first hour after awakening compared to evening chronotypes.

  • Cortisol levels were measured at 0, 30, 45, and 60 minutes post-awakening.
  • Nine individuals were identified as morning chronotypes, while 29 were classified as evening chronotypes.
  • Both awakening time and sleep duration did not account for the differences in cortisol levels between chronotypes.
  • Significant effects of chronotype on cortisol levels were observed on both days of measurement.
  • These findings suggest that chronotype may contribute to individual variability in cortisol response after awakening.

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