Circadian Rhythms, Sleep, Time Perception
Conditions
Keywords
circadian phase delay, Healthy adults
Brief summary
The purpose of this study is to investigate whether the experience of a daily time delay can affect our internal circadian rhythm.
Interventions
BEHAVIORALFixed daily routine
All activities occur at the same time every day
BEHAVIORALDaily time delay
All activities will be delayed by one hour per day over a 5 day period.
Sponsors
University of Aarhus
Independent Research Fund Denmark
Study design
Allocation
RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Masking description
Open-label, single-group basic science study; no masking used.
Intervention model description
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.
Eligibility
Sex/Gender
ALL
Age
23 Years to 45 Years
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Phase shift in circadian rhythm markers | 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
| Measure | Time frame | Description |
|---|---|---|
| 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. | Median reaction time (milliseconds) on a brief psychomotor vigilance task (PVT) six times each day. Participants respond as quickly as possible to visual stimuli presented at random inter-stimulus intervals. For each block, the median reaction time is computed; additional indices such as lapses (responses \> 500 ms) may be derived. Changes in PVT performance across the the 5 days are analysed in relation to circadian phase. |
Countries
Denmark
Contacts
CONTACTAli Amidi, PhD
CONTACTAlisha Guyett, PhD
Outcome results
None listed