The Effect of a Continuous 1-Hour Time Delay on Circadian Rhythms
Overview
- Phase
- Not Applicable
- Status
- Recruiting
- Sponsor
- University of Aarhus
- Enrollment
- 40
- Locations
- 1
- Primary Endpoint
- Phase shift in circadian rhythm markers
Overview
Brief Summary
The purpose of this study is to investigate whether the experience of a daily time delay can affect our internal circadian rhythm.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Single Group
- Primary Purpose
- Basic Science
- Masking
- None
Masking Description
Open-label, single-group basic science study; no masking used.
Eligibility Criteria
- Ages
- 23 Years to 45 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
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
Arms & Interventions
Fixed daily routine
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
Intervention: Fixed daily routine (Behavioral)
Daily time delay of 1 hour
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
Intervention: Daily time delay (Behavioral)
Outcomes
Primary Outcomes
Phase shift in circadian rhythm markers
Time Frame: Comparing samples on days 1, 3, 5
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.
Secondary Outcomes
- 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.)