Light ExposureLipidPRCNCT05276739
Role of Photic and Non-photic Time Cues in Resetting Circadian Rhythms
A study testing Bright Light, Time-restricted eating and Dim light in people with Light Exposure and Meal Timing, run by Brigham and Women's Hospital at 1 site in United States.
Trial summary
The aim of this study is to determine the principal time cue (light or meals) for resetting circadian rhythms in melatonin and metabolic outcomes. Read more about this study
- Who is it for?
- Ages 18 to 30 yearsHealthy volunteers can take part
- Conditions the study is for
- Light Exposure, Meal Timing
- What is being tested?
- Bright Light, Time-restricted eating and Dim light
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 47 participants
- Where
- 1 siteUnited States
- Study dates
- 29 Jul 2022to 31 Jul 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 30 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Aged between 18-30 years
- Healthy (no medical, psychiatric or sleep disorders;
- Non-smoking for at least 6 months;
- Body Mass Index of >18 or <30 kg/m2;
- Able to maintain 8-hour consistent sleep schedule during the study
- Able to refrain from caffeine, alcohol, medication and supplements during the study
Who cannot join
- History of alcohol or substance abuse;
- Positive result on drugs of abuse urine toxicology;
- Current or past history of sleep disorders, including but not limited to obstructive sleep apnea, narcolepsy, insomnia, or any significant sleep complaint
- Psychiatric disorder, or first degree relative with a psychiatric disorder
- Recent acute or chronic medical disorder
- Use of drugs or medication (birth control OK) likely to affect sleep, alertness or light sensitivity, as determined by the investigators
Show all 11Show fewer
- Visual disorder, including but not limited to color blindness, or family history of glaucoma
- Pregnancy or lactation
- Shift work (past 3 years)
- Transmeridian travel (2 or more time zones) in the past 3 months
- Any other reason as determine by the Principal Investigator
Trial locations and contacts
1 site in 1 country.
United States1 site
Brigham and Women's Hospital
Boston, Massachusetts, 02115
About this study
Official title: Determining the Role of Photic and Non-photic Time Cues in Resetting Circadian Rhythms in Humans
The aim of this study is to determine the principal time cue (light or meals) for resetting circadian rhythms in melatonin and metabolic outcomes.
Read the detailed description
The objective of this proposal is to construct and compare PRCs describing the relationship between the timing of light exposure and meals across the 24-hour day and the size and direction of shift in circadian rhythms of circulating lipids and melatonin in humans. Completion of the work will provide mechanistic insight on the role of photic and non-photic cues mediating entrainment of circadian rhythms in humans besides that of melatonin. In this proposal, we will use the same experimental paradigm that we have successfully used previously to characterize and compare PRCs for shifts in melatonin in response to light exposure of different durations and spectra, and as used in our pilot trials demonstrating a robust PRC of lipid circadian rhythms in response to combined photic and non-photic stimuli across the day. We will achieve our objective using a randomized controlled trial in young healthy adults (n=48, 18-30 years) that systematically manipulates the timing of 6.5-hour bright light exposure and 6.5-hour time restricted eating across the 24-hour circadian cycle to specifically:
Aim 1: Determine if light is the primary time cue for resetting melatonin but not lipid circadian rhythms. Hypothesis: The resetting response of circadian rhythms in melatonin but not cholesterol and triglycerides is dependent upon the circadian phase at which a 6.5-hour bright light exposure occurs.
Aim 2: Determine if meal timing is the primary time cue for resetting lipid but not melatonin circadian rhythms. Hypothesis: The resetting response of circadian rhythms in cholesterol and triglycerides but not melatonin is dependent upon the circadian phase at which a 6.5-hour time restricted eating occurs.
Aim 3 (Exploratory): Evaluate the acute effects of eating across the 24-hour day on circulating lipid levels. Hypothesis: The acute effects of 6.5-hour time restricted eating on circulating cholesterol and triglycerides levels are dependent on the circadian phase at which meals are eaten.
- Conditions
- Light Exposure, Meal Timing
- Being tested
- Bright Light, Time-restricted eating, Dim light, 12-h meal window
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Bright LightBehavioural
6.5-hour 10,000 lux light pulse (4100K fluorescent light) centered within the 16-hour wake episode (start 4.75 hour after wake and end 11.25 hour after wake).
Time-restricted eatingBehavioural
6.5-hour restricted meal window (4 meals at 4.75, 6.9, 9.1, 11.25 hours after waking) centered within the 16-hour wake episode.
Dim lightBehavioural
dim light (<3 lux) throughout the 16-hour wake episode
12-h meal windowBehavioural
12-hour restricted meal window (4 meals at 2, 6, 10, and 14 hours after waking) centered within the 16-hour wake episode.
| Study group | Role | What they receive |
|---|---|---|
| Bright light | Experimental | Participants will receive a 6.5-hour 10,000 lux light pulse (4100K fluorescent light) centered within the 16-hour wake episode (start 4.75 hour after wake and end 11.25 hour after wake). Participants will receive 4 identical meals (equal calories and macronutrient content), over a 12-hour interval (meals at 2, 6, 10, and 14 hours after waking) centered within the 16-hour wake episode. Receives: Behavioral: Bright Light; Behavioral: 12-h meal window |
| Time-restricted eating | Experimental | Participants will consume 4 identical meals, as in the other groups, except that the meal window will be restricted to 6.5 hours instead of 12 hours (meals at 4.75, 6.9, 9.1, 11.25 hours after waking) centered within the 16-hour wake episode. Participants will remain in dim light (<3 lux) throughout the 16-hour wake episode. Receives: Behavioral: Time-restricted eating; Behavioral: Dim light |
| Control | Sham comparator | Participants will receive 4 identical meals (equal calories and macronutrient content), over a 12-hour interval (meals at 2, 6, 10, and 14 hours after waking) centered within the 16-hour wake episode. Participants will remain in dim light (<3 lux) throughout the 16-hour wake episode. Receives: Behavioral: Dim light; Behavioral: 12-h meal window |
What is being measured
The primary outcome is the main question the study is designed to answer.
Amplitude of Phase Response Curve of melatonin
Amplitude of phase response curve of melatonin derived by fitting a sinusoidal regression to the individual phase shift data across ~24 hours
Measured: 24 hours
Amplitude of Phase Response Curve of triglyceride
Amplitude of phase response curve of triglyceride derived by fitting a sinusoidal regression to the individual phase shift data across ~24 hours
Measured: 24 hours
Amplitude of Phase Response Curve of cholesterol
Amplitude of phase response curve of cholesterol derived by fitting a sinusoidal regression to the individual phase shift data across ~24 hours
Measured: 24 hours
Secondary outcomes (3)
Area under the curve (AUC) of melatonin
AUC of melatonin
Measured: 6.5 hours during intervention
Area under the curve (AUC) of triglyceride
AUC of triglyceride
Measured: 6.5 hours during intervention
Area under the curve (AUC) of cholesterol
AUC of cholesterol
Measured: 6.5 hours during intervention
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted11 Mar 2022
- Study start29 Jul 2022
- Primary completion31 Jul 2026
- Study completion31 Jul 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Light ExposureStudies of the same condition, open and under way.
- More trials run by Brigham and Women's HospitalThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 3 condition, parallel arm randomized control trial
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 47 participants (actual)
Sponsor and investigators
- Lead sponsor
- Brigham and Women's Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Shadab A Rahman, Brigham and Women's Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05276739
- Sponsor's protocol ID
- 2021P000757
- Acronym
- LipidPRC
- Status last verified
- Aug 2026
- First submitted
- 3 Mar 2022
- Last updated
- 6 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 6 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Determining the Role of Photic and Non-photic Time Cues in Resetting Circadian Rhythms in Humans
- ClinicalTrials.gov ID
- NCT05276739
- Acronym / sponsor ID
- LipidPRC / 2021P000757
- Conditions
- Light Exposure, Meal Timing
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 47 participants (actual)
- Lead sponsor
- Brigham and Women's HospitalUniversity, hospital or other
- Study start
- 29 Jul 2022 (actual)
- Primary completion
- 31 Jul 2026 (actual)
- Study completion
- 31 Jul 2026 (actual)
- First posted
- 11 Mar 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The aim of this study is to determine the principal time cue (light or meals) for resetting circadian rhythms in melatonin and metabolic outcomes.
Detailed description
The objective of this proposal is to construct and compare PRCs describing the relationship between the timing of light exposure and meals across the 24-hour day and the size and direction of shift in circadian rhythms of circulating lipids and melatonin in humans. Completion of the work will provide mechanistic insight on the role of photic and non-photic cues mediating entrainment of circadian rhythms in humans besides that of melatonin. In this proposal, we will use the same experimental paradigm that we have successfully used previously to characterize and compare PRCs for shifts in melatonin in response to light exposure of different durations and spectra, and as used in our pilot trials demonstrating a robust PRC of lipid circadian rhythms in response to combined photic and non-photic stimuli across the day. We will achieve our objective using a randomized controlled trial in young healthy adults (n=48, 18-30 years) that systematically manipulates the timing of 6.5-hour bright light exposure and 6.5-hour time restricted eating across the 24-hour circadian cycle to specifically:
Aim 1: Determine if light is the primary time cue for resetting melatonin but not lipid circadian rhythms. Hypothesis: The resetting response of circadian rhythms in melatonin but not cholesterol and triglycerides is dependent upon the circadian phase at which a 6.5-hour bright light exposure occurs.
Aim 2: Determine if meal timing is the primary time cue for resetting lipid but not melatonin circadian rhythms. Hypothesis: The resetting response of circadian rhythms in cholesterol and triglycerides but not melatonin is dependent upon the circadian phase at which a 6.5-hour time restricted eating occurs.
Aim 3 (Exploratory): Evaluate the acute effects of eating across the 24-hour day on circulating lipid levels. Hypothesis: The acute effects of 6.5-hour time restricted eating on circulating cholesterol and triglycerides levels are dependent on the circadian phase at which meals are eaten.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 3
- Model description
- 3 condition, parallel arm randomized control trial
| Arm | Type | Receives |
|---|---|---|
| Bright light | Experimental | Behavioral: Bright Light, Behavioral: 12-h meal windowParticipants will receive a 6.5-hour 10,000 lux light pulse (4100K fluorescent light) centered within the 16-hour wake episode (start 4.75 hour after wake and end 11.25 hour after wake). Participants will receive 4 identical meals (equal calories and macronutrient content), over a 12-hour interval (meals at 2, 6, 10, and 14 hours after waking) centered within the 16-hour wake episode. |
| Time-restricted eating | Experimental | Behavioral: Time-restricted eating, Behavioral: Dim lightParticipants will consume 4 identical meals, as in the other groups, except that the meal window will be restricted to 6.5 hours instead of 12 hours (meals at 4.75, 6.9, 9.1, 11.25 hours after waking) centered within the 16-hour wake episode. Participants will remain in dim light (<3 lux) throughout the 16-hour wake episode. |
| Control | Sham comparator | Behavioral: Dim light, Behavioral: 12-h meal windowParticipants will receive 4 identical meals (equal calories and macronutrient content), over a 12-hour interval (meals at 2, 6, 10, and 14 hours after waking) centered within the 16-hour wake episode. Participants will remain in dim light (<3 lux) throughout the 16-hour wake episode. |
Who may qualify
- Ages
- 18 to 30 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- Aged between 18-30 years
- Healthy (no medical, psychiatric or sleep disorders;
- Non-smoking for at least 6 months;
- Body Mass Index of >18 or <30 kg/m2;
- Able to maintain 8-hour consistent sleep schedule during the study
Key exclusion criteria (11 listed)
- History of alcohol or substance abuse;
- Positive result on drugs of abuse urine toxicology;
- Current or past history of sleep disorders, including but not limited to obstructive sleep apnea, narcolepsy, insomnia, or any significant sleep complaint
- Psychiatric disorder, or first degree relative with a psychiatric disorder
- Recent acute or chronic medical disorder
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Bright Light6.5-hour 10,000 lux light pulse (4100K fluorescent light) centered within the 16-hour wake episode (start 4.75 hour after wake and end 11.25 hour after wake). | Behavioural | Bright light |
| Time-restricted eating6.5-hour restricted meal window (4 meals at 4.75, 6.9, 9.1, 11.25 hours after waking) centered within the 16-hour wake episode. | Behavioural | Time-restricted eating |
| Dim lightdim light (<3 lux) throughout the 16-hour wake episode | Behavioural | Control, Time-restricted eating |
| 12-h meal window12-hour restricted meal window (4 meals at 2, 6, 10, and 14 hours after waking) centered within the 16-hour wake episode. | Behavioural | Bright light, Control |
Primary outcome
Amplitude of Phase Response Curve of melatonin
Time frame: 24 hours
Amplitude of phase response curve of melatonin derived by fitting a sinusoidal regression to the individual phase shift data across ~24 hours
Amplitude of Phase Response Curve of triglyceride
Time frame: 24 hours
Amplitude of phase response curve of triglyceride derived by fitting a sinusoidal regression to the individual phase shift data across ~24 hours
Amplitude of Phase Response Curve of cholesterol
Time frame: 24 hours
Amplitude of phase response curve of cholesterol derived by fitting a sinusoidal regression to the individual phase shift data across ~24 hours
3 secondary outcomes
Area under the curve (AUC) of melatonin
Time frame: 6.5 hours during intervention
Area under the curve (AUC) of triglyceride
Time frame: 6.5 hours during intervention
Area under the curve (AUC) of cholesterol
Time frame: 6.5 hours during intervention
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Aug 2026.
- Individual participant dataSharing planned: No
Related trials for Light Exposure
Recruiting
Circadian Light Exposure Adjustment for Restfulness
Sleep Onset Latency
Not yet recruiting
Therapeutic Induction of Dermal Remodeling in Veterans to Prevent Actinic Neoplasia Caused by Chronic Environmental Exposure to Ultraviolet Radiation
Nonmelanoma Skin Cancer, Actinic Keratosis
Not yet recruiting
ROSA-B: ALAN Exposure and Brain Health in Midlife Women With VMS
Women in the Menopausal Period
RecruitingPhase 1
The Impact of Light Exposure on Cognitive Function in Classrooms
Healthy
Active, not recruitingEarly Phase 1
Effect of Topical Sulforaphane on Skin Aging and With Ultraviolet and Visible Light Exposure
Skin Aging
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Bright Light, Time-restricted eating and Dim light in people with Light Exposure and Meal Timing, run by Brigham and Women's Hospital at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 6 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Amplitude of Phase Response Curve of melatonin (time frame: 24 hours). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Aug 2026.