Effects of Daylight and Physical Activity on Sleep and Circadian Rhythm

Beneficial Effects of Daytime Light Exposure and Physical Activity on the Human Circadian Clock and Sleep

NA · University Hospital, Basel, Switzerland · NCT05513547

This study is testing how different types of daylight and physical activity can help people sleep better and adjust their body clocks.

Quick facts

PhaseNA
Study typeInterventional
Enrollment48 (estimated)
Ages18 Years to 35 Years
SexAll
SponsorUniversity Hospital, Basel, Switzerland (other)
Locations1 site (Basel)
Trial IDNCT05513547 on ClinicalTrials.gov

What this trial studies

This study investigates how exposure to different types of daylight and levels of physical activity can shift the human circadian clock and improve sleep quality. Participants will experience three different light conditions during the day and will be assigned to either a hiking activity or a rest period. The primary endpoint is the change in dim-light melatonin onset (DLMO), which will help determine the impact of these interventions on sleep. The study aims to clarify the roles of various light wavelengths and physical activity on the biological clock and sleep patterns.

Who should consider this trial

Good fit: Ideal candidates for this study are healthy adults aged 18-35 with a normal body mass index and moderate physical activity levels.

Not a fit: Patients with chronic sleep disorders or significant medical conditions may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to improved sleep quality and circadian rhythm regulation for individuals exposed to inadequate light conditions.

How similar studies have performed: Other studies have shown promising results in improving sleep and circadian rhythms through light exposure and physical activity, suggesting this approach may be effective.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age: 18-35 years
* Body Mass Index: 18.5-24.9 (i.e., normal weight according to World Health Organization (WHO) criteria)
* Moderate cardiorespiratory fitness levels, moderate level of endurance training according to the category "moderate physical activity" (category 2) of the International Physical Activity Questionnaire (IPAQ) short form
* Informed consent as documented by signature of the participant

Exclusion Criteria:

* Self-reported pregnancy
* Investigator's family members, employees, or other dependent persons
* Chronic or debilitating medical (including psychiatric) conditions; normal state of health will be established on the basis of questionnaires and the examination by the physician in charge. Illnesses that would be a reason for exclusion are:

  * Sleep disorders: Narcolepsy, sleep apnea (apnea index \> 10), periodic limb movements (PLM index \> 15), insomnia (polygraphically recorded sleep efficiency \< 70% or Pittsburgh Sleep Quality Index (PSQI) index \> 5), hypersomnia
  * Chronobiological disorders: hypernychthemeral sleep-wake cycle, delayed or advanced sleep phase syndrome
  * Psychiatric disorders
  * Somatic diseases: cardiovascular, respiratory, gastrointestinal, haemopoietic, visual and immune system diseases, neurological disorders, infectious diseases, allergies (e.g., skin allergies, acute hay fever), thrombocytopenia or other dysfunctions of blood platelets
* Drug use: volunteers must not consume any drugs (including nicotine and alcohol) for the entire duration of the study with no history of drug or alcohol dependency. This will be ensured by the use of a urine multi-drug screen at every experimental visit.
* Medication that could affect outcome parameters
* Shift work \< 3 months prior to study intake
* Transmeridian travel (\> 2 time zones) \< 1 month prior to study intake
* Extreme chronotype (Munich Chronotype Questionnaire \[MCTQ\] \<2 or \>7)
* Extremely long/short sleep duration (subjective sleep duration on workdays outside 6-10h according to the MCTQ)
* Abnormal colour vision, vision disorders (other than e.g., mild myopia corrected with contact lenses)
* Inability to understand and/or follow procedures
* Non-adherence to the circadian stabilization protocol during the five days prior to and between the experimental visits (deviation of \>30min form scheduled times more than twice or on the day of the study visit)

Where this trial is running

Basel

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Circadian System, daytime light exposure, human circadian clock, Dim-Light Melatonin Onset, nocturnal light exposure, intrinsically photosensitive retinal ganglion cells, retinal photoreceptors, photopic illuminance

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.