The Clockwise Chronometric Test (CCT) is a continuous development of the RBUB-Chronometric Test for commercial and scientific utilisation. 

The purpose of the CCT is to quantitatively determine the circadian phenotypes of individuals by looking at the temporal structure of their sleep patterns, daily routines, and activity patterns, assessing weekdays, weekends, and free days separately. The CCT was created by Dr Roland Brandstaetter and validated with more than 10,000 participants at present (2020). It takes into account two widely used questionnaires, the Munich ChronoType Questionnaire (MCTQ), and the Horne-Östberg Morningness-Eveningness Questionnaire (MEQ); The MCTQ is quantitative but primarily based on a single parameter, i.e. mid-sleep on free days, while the Horne-Ostberg MEQ is entirely based on hypothetical and subjective questions.

The CCT is the first and only available multivariate analysis tool for the determination of the differences between the circadian entrainment status of individuals, i.e. circadian phenotype. It considers all relevant information that can be obtained from the MCTQ and MEQ and contains specific questions that allow a reliable and accurate analysis of circadian phenotype and a clear distinction between endogenous and external factors, including entraining and masking factors. The CCT covers a total of 55 parameters all of which can be quantitatively analysed and cross correlated with each other. As such, the test allows a comprehensive analysis of body clock function as a whole.

The test is modular and represents the only available chronometric test that can be adjusted to different target groups, including shift-workers, athletes, night-workers, University students, and many others.

The determination of circadian phenotype is based on comparing weekday, weekend and free day circadian parameters. For example, weekend wake up times are cross correlated with weekday/free day wake up times, weekday/weekend/free day sleep onset times, and further parameters to produce particular scores of circadian entrainment, separately for wake up times, sleep onset times, sleep durations, etc, all of which are important parameters for defining circadian phenotypes. Scores are then compared according to a specific priority list and masking factors, which might mislead in the interpretation of circadian phenotype, are omitted. This then enables a consistent and fully reliable determination of circadian phenotype. The data of each individual are then fed into the ‘Clockwise Cloud’, a data-base of more than 10,000 individuals to check for compatibility with ECT, ICT, or LCT. A series of further validations of a number of parameters is performed to validate categorisation into phenotypes.