Paper

Life between clocks: daily temporal patterns of human chronotypes

Roenneberg T, Wirz-Justice A, Merrow M
J Biol Rhythms 20032003
Published articlePublication date: Feb 2003Added to atlas: Oct 15, 2026Source
Citations2,407Crossref referencesChecked Oct 16, 2026
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Activity counts measure attention, not model quality. Missing counts are unknown. Publication status follows the linked source; a listed venue alone does not confirm peer review.

Munich ChronoType Questionnaire (MCTQ): chronotype as mid-sleep on free days (later corrected for sleep debt, MSFsc). Directly computable from wearable sleep timing on free days.

  • Venue: J Biol Rhythms 2003
At a glance
Venue
J Biol Rhythms 2003
Published
2003
arXiv
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Added
Oct 15, 2026

Abstract

Human behavior shows large interindividual variation in temporal organization. Extreme “larks” wake up when extreme “owls” fall asleep. These chronotypes are attributed to differences in the circadian clock, and in animals, the genetic basis of similar phenotypic differences is well established. To better understand the genetic basis of temporal organization in humans, the authors developed a questionnaire to document individual sleep times, self-reported light exposure, and self-assessed chronotype, considering work and free days separately. This report summarizes the results of 500 questionnaires completed in a pilot study. Individual sleep times show large differences between work and free days, except for extreme early types. During the workweek, late chronotypes accumulate considerable sleep debt, for which they compensate on free days by lengthening their sleep by several hours. For all chronotypes, the amount of time spent outdoors in broad daylight significantly affects the timing of sleep: Increased self-reported light exposure advances sleep. The timing of self-selected sleep is multifactorial, including genetic disposition, sleep debt accumulated on workdays, and light exposure. Thus, accurate assessment of genetic chronotypes has to incorporate all of these parameters. The dependence of human chronotype on light, that is, on the amplitude of the light:dark signal, follows the known characteristics of circadian systems in all other experimental organisms. Our results predict that the timing of sleep has changed during industrialization and that a majority of humans are sleep deprived during the workweek. The implications are far ranging concerning learning, memory, vigilance, performance, and quality of life.

Verbatim fromthe publisher's DOI record· Publisher licence: https://journals.sagepub.com/page/policies/text-and-data-mining-license

Life between clocks: daily temporal patterns of human chronotypes: ChatPPG research summary card

Cite

@article{roennebergmctqlifebetwee2003,
  title = {{Life between clocks: daily temporal patterns of human chronotypes}},
  author = {Roenneberg T and Wirz-Justice A and Merrow M},
  year = {2003},
  journal = {J Biol Rhythms 2003},
  doi = {10.1177/0748730402239679}
}

History

  1. Added to the ChatPPG research hub