Does a daily one-hour clock delay change your body clock?

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

This in-laboratory protocol enrolls healthy cohabiting heterosexual couples who maintain a fixed daily routine while experiencing a continuous one-hour daily time delay over five days. Both partners must meet screening criteria including a normative chronotype, regular sleep-wake timing, low seasonality, and absence of sleep or mood disorders. The laboratory setting controls routine and timing so participants' circadian timing can be tracked across the manipulation. The design isolates the effect of a small, repeated clock delay on internal circadian rhythms in a controlled environment.

Why it matters

Who can join: the full rules

Inclusion Criteria

* Healthy adults aged 23-45 years
* Part of a heterosexual, cohabiting couple willing to participate together in a five-day in-laboratory study
* Both partners meet all inclusion criteria
* 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

Exclusion Criteria

* 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

Where it's running

• Aarhus University, Department of Psychology and Behavioural Sciences
  Aarhus, Denmark Recruiting

Study contacts

• Study coordinator: Ali Amidi, PhD
• Email: ali@psy.au.dk
• Phone: +4587165305

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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.