How your body clock changes how you perceive time

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 Danish-speaking adults aged 23–45 who are clearly morning- or evening-type complete two counterbalanced lab sessions on the same day: one at their preferred time and one at the opposite time. In each session participants perform brief computerized tasks measuring time estimation/production, duration discrimination, vigilance (psychomotor vigilance task), decision-making, responses to social information, and simple color-vision tests while completing short sleepiness and mood questionnaires before, during, and after testing. A subset wears wrist actigraphy and keeps a sleep diary for seven days before testing to characterize habitual sleep–wake timing. Sessions are conducted under standardized conditions with no visible clocks and pre-session restrictions on caffeine and exercise to control for external influences.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* Aged 23 to 45 years
* Able to understand and communicate in Danish
* Completed at least upper secondary education (e.g., gymnasium)
* Categorized as either a Morning Type (MT) or Evening Type (ET) based on standardized chronotype assessments:

  * Munich Chronotype Questionnaire (MCTQ):

    * MT: sleep midpoint on free days (MSFsc) ≤ 03:00
    * ET: sleep midpoint on free days (MSFsc) ≥ 05:00
  * Morningness-Eveningness Questionnaire (MEQ):

    * One of four defined chronotype categories (definitely morning, moderately morning, moderately evening, definitely evening).

Exclusion Criteria:

* Current engagement in shift work, rotating schedules, or other forms of irregular sleep-wake timing
* Diagnosis of any neurological, psychiatric, or sleep-related disorder (e.g., insomnia, narcolepsy, sleep apnea)
* Use of medications that affect sleep, alertness, or circadian functioning (e.g., melatonin, stimulants, antidepressants)
* International travel across time zones within the four weeks preceding study participation
* Are classified as having an intermediate chronotype based on validated chronotype assessments (MCTQ or MEQ), as this group does not provide the necessary contrast to evaluate circadian alignment effects.

Where it's running

• Cognition and Behavior Lab
  Aarhus, Denmark Recruiting

Study contacts

• Study coordinator: Ali Amidi, PhD
• Email: ali@psy.au.dk
• Phone: +45 87165305

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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.