Chronotype and time-of-day test of time perception in morning and evening types

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

Healthy adults classified as morning-type or evening-type complete the same set of time-perception tasks twice, once in the morning and once in the evening, across three international sites. The design examines whether a circadian-timed match (synchrony) improves time-perception accuracy compared with a mismatch, using a 2x2 mixed design replicated at each site. Secondary outcomes include timing precision, subjective passage of time, sleepiness, mood, color vision with and without blue-blocking glasses, and perceptual decision-making. Participants are screened for chronotype, sleep quality, and vision, and attend two laboratory sessions with standardized measures. The study aims to assess generalisability of the synchrony effect across cultures and locations.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* Healthy adult, 18-40 years
* Clear morning-type or evening-type on the Morningness-Eveningness Questionnaire (MEQ-SA); intermediate types excluded (state exact cut-offs, e.g. evening-type 41 or below, morning-type 59 or above)
* Normal or corrected-to-normal visual acuity
* Normal colour vision (e.g. Ishihara screening)
* Fluent in the testing-site language (Danish, Chinese, or English)
* Able to attend both an early-morning (about 08:00) and a late-evening (about 22:00) session

Exclusion Criteria:

* Intermediate chronotype (MEQ in the middle band)
* Night or rotating shift work in the past 3 months, or recent trans-meridian travel (more than 2 time zones in the past 4 weeks)
* Diagnosed sleep disorder (e.g. insomnia, sleep apnoea)
* Current psychiatric or neurological disorder
* Use of sleep medication or psychoactive or CNS-active drugs
* Colour-vision deficiency
* Substance-use disorder

Where it's running

• Child Development Centre
  Hong Kong, Hong Kong Recruiting

Study contacts

• Study coordinator: Cehao Yu, PhD
• Email: cehao.yu@polyu.edu.hk
• Phone: +852 61570422

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.