Human Circadian Phenotyping and Diurnal Performance Testing in the Real World

Elise R Facer-Childs, Benita Middleton, Andrew P Bagshaw, Debra J Skene

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
191 Downloads (Pure)


In our continuously developing 'around the clock' society, there is a need to increase our understanding of how changes in biology, physiology and psychology influence our health and performance. Embedded within this challenge, is the increasing need to account for individual differences in sleep and circadian rhythms, as well as to explore the impact of time of day on performance in the real world. There are a number of ways to measure sleep and circadian rhythms from subjective questionnaire-based methods to objective sleep/wake monitoring, actigraphy and analysis of biological samples. This paper proposes a protocol that combines multiple techniques to categorize individuals into Early, Intermediate or Late circadian phenotype groups (ECPs/ICPs/LCPs) and recommends how to conduct diurnal performance testing in the field. Representative results show large differences in rest-activity patterns derived from actigraphy, circadian phase (dim light melatonin onset and peak time of cortisol awakening response) between circadian phenotypes. In addition, significant differences in diurnal performance rhythms between ECPs and LCPs emphasizes the need to account for circadian phenotype. In summary, despite the difficulties in controlling influencing factors, this protocol allows a real-world assessment of the impact of circadian phenotype on performance. This paper presents a simple method to assess circadian phenotype in the field and supports the need to consider time of day when designing performance studies.

Original languageEnglish
Article number e60448
JournalJournal of Visualized Experiments
Issue number158
Publication statusPublished - 7 Apr 2020


  • Actigraphy
  • Behavior
  • Chronotype
  • Circadian phenotype
  • Circadian rhythms
  • Cortisol awakening response
  • Dim light melatonin onset
  • Individual differences
  • Issue 158
  • Performance
  • Sleep

ASJC Scopus subject areas

  • General Neuroscience
  • General Chemical Engineering
  • General Biochemistry,Genetics and Molecular Biology
  • General Immunology and Microbiology


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