Circadian Timing and Time Perception in Healthy Adults

Summary

This study examines how a person's natural daily rhythm ("chronotype") affects the way time is experienced and judged. Healthy Danish-speaking adults (23-45 years) who are clearly morning-type or evening-type will complete two lab sessions in a crossover design: one at their preferred time of day (e.g., morning for morning-types) and one at the opposite time (misaligned). In each session, participants do brief computerized tasks that measure time estimation/production, vigilance (psychomotor vigilance task), decision-making, and responses to social information, plus simple color-vision tasks. Short questionnaires about sleepiness, mood, fatigue, and the subjective "passage of time" are collected before, during, and after testing. A subset will wear a wrist actigraphy device for one week beforehand to characterize sleep-wake patterns.

Testing is conducted under standardized lab conditions with scheduled breaks. The main goal is to determine whether time judgments and vigilance are less accurate during the misaligned session and whether decision-making and social responses also vary with circadian timing. Risks are minimal and mainly relate to temporary tiredness when tested at a non-preferred time; participants may stop at any time. Participation is voluntary. Data are pseudonymized and handled under GDPR. Participants receive DKK 300 after completing both sessions (pro-rated if they withdraw early). Results will be published regardless of outcome, and de-identified data/code will be shared after publication.This study examines how a person's natural daily rhythm ("chronotype") affects the way time is experienced and judged. Healthy Danish-speaking adults (23-45 years) who are clearly morning-type or evening-type will complete two lab sessions in a crossover design: one at their preferred time of day (e.g., morning for morning-types) and one at the opposite time (misaligned). In each session, participants do brief computerized tasks that measure time estimation/production, vigilance (psychomotor vigilance task), decision-making, and responses to social information, plus simple color-vision tasks. Short questionnaires about sleepiness, mood, fatigue, and the subjective "passage of time" are collected before, during, and after testing. A subset will wear a wrist actigraphy device for one week beforehand to characterize sleep-wake patterns.

Testing is conducted under standardized lab conditions with scheduled breaks. The main goal is to determine whether time judgments and vigilance are less accurate during the misaligned session and whether decision-making and social responses also vary with circadian timing. Risks are minimal and mainly relate to temporary tiredness when tested at a non-preferred time; participants may stop at any time. Participation is voluntary. Data are pseudonymized and handled under GDPR. Participants receive DKK 300 after completing both sessions (pro-rated if they withdraw early). Results will be published regardless of outcome, and de-identified data/code will be shared after publication.

Conditions

• Circadian Rhythm
• Time Perception

Interventions

BEHAVIORAL

Session timing relative to chronotype

Two-period, two-sequence crossover manipulation of testing time. Each participant completes both sessions: (1) circadian-congruent timing (morning types tested in the morning; evening types in the evening) and (2) circadian-incongruent timing (opposite time). Session order is randomized (AB/BA). Sessions are run morning and evening on the same day with a substantial interval; no visible clocks; 12-h pre-session caffeine/strenuous-exercise restriction; standardized lab light/temperature. Primary outcomes: time-estimation/production bias and PVT lapses/RT.

Sponsors & Collaborators

• University of Aarhus

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

NONE

Model

CROSSOVER

Eligibility

Min Age

23 Years

Max Age

45 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2025-10-25

Primary Completion

2027-04-30

Completion

2027-06-30

Countries

• Denmark

Study Locations