The Effect of a Continuous 1-Hour Time Delay on Circadian Rhythms

NCT07317349 | Recruiting DMC

• 2 other identifiers: 1-10-72-143-2510.46540/425600108B
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of this study is to investigate whether the experience of a daily time delay can affect our internal circadian rhythm.

Conditions

Time Perception; Circadian Rhythms; Sleep

Keywords

circadian phase delay; Healthy adults

Outcome Measures

Primary Outcomes (1)

• Phase shift in circadian rhythm markers

  The primary outcome is the timing of dim light melatonin onset, a marker of circadian phase. Saliva samples will be collected at regular intervals under dim light, and the time when melatonin exceeds 3 pg/mL will be recorded for each participant. This allows measurement of circadian phase shifts across conditions.

  Comparing samples on days 1, 3, 5

Secondary Outcomes (1)

• Psychomotor Vigilance Task (PVT) Median Reaction Time

  Performance will be measured at regular intervals on days 1 - 5 to track changes over the course of the study.

Study Arms (2)

Fixed daily routine

EXPERIMENTAL

All activities occur at the same time every day. During the five days, participants will have to complete various daily tests and also be asked to provide 8 saliva samples during days 1, 3, and 5

Behavioral: Fixed daily routine

Daily time delay of 1 hour

EXPERIMENTAL

All activities will be delayed by one hour. During the five days, participants will have to complete various daily tests and also be asked to provide 8 saliva samples during days 1, 3, and 5

Behavioral: Daily time delay

Interventions

Fixed daily routine BEHAVIORAL

All activities occur at the same time every day

Fixed daily routine

Daily time delay BEHAVIORAL

All activities will be delayed by one hour per day over a 5 day period.

Daily time delay of 1 hour

Eligibility Criteria

• Age: 23 Years - 45 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy adults aged 23-45 years
• Part of a heterosexual, cohabiting couple willing to participate together in a five-day in-laboratory study
• Completion of at least upper-secondary education
• Maintain a regular sleep-wake schedule
• Habitual sleep timing within a normative range (non-extreme chronotype), assessed using the Morningness-Eveningness Questionnaire (MEQ) or the Munich Chronotype Questionnaire (MCTQ)
• Both partners fall within the acceptable chronotype range to ensure aligned sleep-wake patterns
• Low seasonality scores on the Seasonal Pattern Assessment Questionnaire (SPAQ)
• Free from underlying sleep or mood disorders

You may not qualify if:

• Engages in night-shift work or maintains an irregular work or sleep schedule
• International travel involving a time-zone change of more than two hours within the past two months, or anticipated travel before study completion
• Diagnosed neurological, psychiatric, or sleep disorder (e.g., insomnia, sleep apnea, bipolar disorder)
• High risk of sleep apnea, defined as a Berlin Questionnaire score \>2 (Lauritzen et al., 2018)
• Use of medications known to affect sleep, alertness, melatonin secretion, or circadian timing
• Unable or unwilling to comply with behavioral restrictions, including refraining from electronic devices displaying time cues unless clocks are removed and devices are disconnected from Wi-Fi
• Unable or unwilling to comply with consumption restrictions, including abstaining from caffeine, alcohol, and melatonin-rich foods during the study
• Extreme chronotype, defined as a habitual midsleep time outside 03:00-05:00 on the MCTQ or classification as an extreme morning or extreme evening type on the MEQ
• Daily caffeine consumption exceeding 400 mg (approximately 4-5 cups of coffee)
• Current smoker or smoking within the past six months

Sponsors & Collaborators

• University of Aarhus: lead
• Independent Research Fund Denmark: collaborator

Study Sites (1)

Aarhus University, Department of Psychology and Behavioural Sciences

Aarhus, 8000, Denmark

RECRUITING

Related Links

• Sleep \& Circadian Psychology Research Unit - Aarhus University (information on research in sleep, circadian rhythms)

Central Study Contacts

Ali Amidi, PhD

CONTACT

+4587165305; ali@psy.au.dk

Alisha Guyett, PhD

CONTACT

alisha.guyett@psy.au.dk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: Open-label, single-group basic science study; no masking used.
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Participating couples will need to live in this environment for 5 consecutive days. By lottery draw, you as a couple will either be exposed to a fixed daily routine, where all activities occur at the same time every day, or a daily time delay of 1 hour, where all activities will be delayed by one hour.

Study Record Dates

• First Submitted: December 19, 2025
• First Posted: January 5, 2026
• Study Start: December 20, 2025
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): August 30, 2027
• Last Updated: January 16, 2026

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ANALYTIC CODE
• Time Frame: De-identified individual participant data and supporting documents will be made available beginning within 12 months after publication of the main results article and will remain available for at least 5 years thereafter.
• Access Criteria: De-identified individual participant data (IPD), together with the study protocol, statistical analysis plan, and analytic code, will be available to qualified researchers affiliated with recognised research institutions who submit a methodologically sound proposal and obtain any required ethical or institutional approvals. Requests should describe the planned analyses and data needed. Approved requesters will sign a data use agreement prohibiting re-identification of participants and requiring appropriate data security. Data will be shared via secure transfer or a controlled-access repository approved by Aarhus University.

Locations

DK (1)