Circadian Type Inventory (CTI)

  • Azmeh ShahidEmail author
  • Kate Wilkinson
  • Shai Marcu
  • Colin M. Shapiro


The CTI was initially developed to identify individuals capable of adapting to shift work. Thus, the scale assesses two factors that influence a person’s ability to alter his or her sleeping rhythms: rigidity/flexibility of sleeping habits and ability/inability of overcome drowsiness [1]. Since its creation, the scale has undergone a number of revisions to improve its psychometric properties. An 18-item version was used as part of the larger Standard Shiftwork Index (SSI) in a study conducted by Barton and colleagues [2]. This shorter scale was then reduced and altered to make an 11 item scale by De Milia et al. [3].


  1.  1.
    Folkard, S. & Monk, T. H. (1979). Towards a predictive test of adjustment to shiftwork. Ergonomics, 22(1), 79–91.PubMedCrossRefGoogle Scholar
  2.  2.
    Barton, J., Spelton, E. R., Totterdell, P. A., Smith, L. R., Folkard, S., & Costa, G. (1995). The standard shiftwork index: a battery of questionnaires for assessing shiftwork related problems. Work and Stress, 9, 4–30.CrossRefGoogle Scholar
  3.  3.
    De Milia, L., Smith, P. A., & Folkard, S. (2004). Refining the psychometric properties of the circadian type inventory. Personality and Individual Differences, 36, 1953–1964.CrossRefGoogle Scholar
  4.  4.
    Smith, P. A., Brown, D. F., Di Milia, L., & Wragg, C. (1993). The use of the circadian type inventory constructs of vigour and rigidity. Ergonomics, 36, 169–176.PubMedCrossRefGoogle Scholar
  5.  5.
    Di Milia, L., Smith, P. A., & Folkard, S. (2005). A validation of the revised circadian type inventory in a working sample. Personality and Individual Differences, 39, 1293–1305.CrossRefGoogle Scholar

Representative Studies Using Scale

  1. Baehr, E. K., Revelle, W., & Eastman, C. I. (2000). Individual difference in the phase and amplitude of the human circadian temperature rhythm: with an emphasis on morningness-eveningness. Journal of Sleep Research, 9, 117–127.PubMedCrossRefGoogle Scholar
  2. Tucker, P., Smith, L., Macdonald, I., & Folkard, S. (2000). Effects of direction of rotation in continuous and discontinuous 8 hour shift systems. Occupation and Environmental Medicine, 57, 678–684.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Azmeh Shahid
    • 1
    Email author
  • Kate Wilkinson
    • 1
  • Shai Marcu
    • 2
  • Colin M. Shapiro
    • 3
  1. 1.University of Toronto The Youthdale Child and Adolescent Sleep CentreTorontoCanada
  2. 2.University of Toronto The Youthdale Child and Adolescent Sleep CentreTorontoCanada
  3. 3.Department of PsychiatryUniversity of Toronto The Youthdale Child and Adolescent Sleep CentreTorontoCanada

Personalised recommendations