How your body clock changes how you perceive time

How Do Individual Differences in Circadian Rhythms Influence Time Perception?

This project will test whether being tested at your preferred or opposite time of day changes time estimation, time production, and vigilance in healthy Danish adults who are clearly morning- or evening-types.

Quick facts

• Phase: NA
• Study type: Interventional
• Enrollment: 128 (estimated)
• Ages: 23 Years to 45 Years
• Sex: All
• Sponsor: University of Aarhus (other)
• Locations: 1 site (Aarhus)
• Trial ID: NCT07292597 on ClinicalTrials.gov

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.

Who should consider this trial

Good fit: Healthy Danish-speaking adults aged 23–45 with at least upper secondary education who are clearly categorized as morning-type or evening-type on standard chronotype questionnaires.

Not a fit: People with intermediate chronotypes, active shift workers, recent trans-meridian travelers, those with sleep/neurologic/psychiatric disorders, or taking medications that affect sleep or alertness are unlikely to qualify or benefit from the findings.

Why it matters

Potential benefit: If successful, the results could help identify how aligning daily schedules with individual chronotype improves time judgments and alertness and inform better timing of work or testing schedules.

How similar studies have performed: Prior circadian research has demonstrated effects of timing on vigilance and cognition, but within-person effects of circadian alignment specifically on time perception are relatively novel and not well characterized.

Eligibility criteria

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 this trial is running

Aarhus

• Cognition and Behavior Lab — Aarhus, Denmark (RECRUITING)

Study contacts

• Study coordinator: Ali Amidi, PhD

Conditions: Circadian Rhythm, Time Perception, chronotype, circadian misalignment, duration discrimination, time production, time estimation