ChronobiologyALTNCT04753190
Light Timing Study
A study testing Baseline Sleep Satiation and Phase Stabilization and Gradually Shifted Sleep in people with Chronobiology and Light, run by Rush University Medical Center at 1 site in United States.
Trial summary
Chronic circadian misalignment and sleep restriction peak during late adolescence, and are associated with morning daytime sleepiness, poor academic performance, conduct problems, depressed mood, suicidal ideation, substance use, insulin resistance, and obesity. Read more about this study
- Who is it for?
- Ages 18 to 20 yearsHealthy volunteers can take part
- Conditions the study is for
- Chronobiology, Light, Sleep
- What is being tested?
- Baseline Sleep Satiation and Phase Stabilization and Gradually Shifted Sleep
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 84 participants
- Where
- 1 siteUnited States
- Study dates
- 22 Aug 2022to 18 May 2025
- 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 20 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- between 18-20 years old
- lives in or near Chicago, IL
Who cannot join
None listed.
Trial locations and contacts
1 site in 1 country.
United States1 site
Rush University Medical Center
Chicago, Illinois, 60612
About this study
Official title: Adolescent Circadian Phase Shifts: Novel Time-of-day Targets for Bright Light
Chronic circadian misalignment and sleep restriction peak during late adolescence, and are associated with morning daytime sleepiness, poor academic performance, conduct problems, depressed mood, suicidal ideation, substance use, insulin resistance, and obesity. Bright light exposure from light boxes can shift rhythms earlier (phase advance) to facilitate earlier sleep onset and reduce morning circadian misalignment and the associated risks. To phase advance circadian rhythms, the investigators' PRCs showed that the ideal time to begin light exposure was slightly before wake-up time and light should be avoided around bedtime because this is when light produces maximum phase delay shifts. An unexpected finding from these results, however, was a second advancing region in the afternoon (~6 to 9 h after habitual wake-up time) suggesting that afternoon light may have more circadian phase advancing ability than traditionally thought. The overall goal of this mechanistic study is to follow-up on the unexpected PRC findings and test whether individually-timed afternoon light alone and in combination with morning bright light can shift circadian rhythms earlier in older adolescents. Four groups will be compared in a randomized parallel group design: afternoon bright light, morning bright light, morning + afternoon bright light, and a dim room light control. Adolescents will complete a 2-week protocol. After a baseline week with a stable sleep schedule, adolescents will live in the laboratory for 7 days. Sleep/dark and the time of bright light exposure will gradually shift earlier. Bright light (~5000 lux) will be timed individually based on his/her stable baseline sleep schedule. The first 3-h morning bright light exposure will begin 1 h before wake on the first morning. The first 3-h afternoon bright light exposure will begin 5 h after wake. The morning + afternoon exposures will begin at the same times, but each exposure will be 1.5 h so that a total of 3 h of bright light per day will be given to each group except the dim light control group. Phase shifts of the circadian clocks marked by the dim light melatonin onset (DLMO) is the main outcome. Investigators hypothesize that afternoon bright light will work synergistically with morning bright light to produce larger shifts than morning or afternoon bright light alone. These data could challenge the current understanding of how to use bright light to shift circadian rhythms earlier.
Read the detailed description
Participants will complete a 14-day protocol. On days 1-7, participants will sleep at home on a stable sleep schedule that requires 9 h of time in bed in the dark. This will ensure that participants are not sleep deprived before beginning the lab sessions. Wake time will be the average of the self-reported wake-up time (± 15 mins) before the study begins measured from pre-study sleep logs collected for a week or more. Bedtime will be 9 h before wake-up time. A device worn on the wrist that measures activity (actigraph), sleep diaries, and daily telephone messages will monitor compliance to the sleep schedule. Participants will visit the lab at least once during this week to download and review their data. If participants are not compliant to the sleep schedule, they will be dropped from the study.
On days 8-13, participants will live in the laboratory for seven days. On day 8, participants will arrive at the laboratory in the afternoon, and shortly after, will begin a baseline circadian phase assessment to determine baseline dim light melatonin onset (DLMO), a reliable marker of the circadian timing system. On day 9, participants will sleep on their stable 9-h sleep schedule in the laboratory. Their 9-h fixed sleep schedule will be shifted by 1 h per day over 3 days. Participants will sleep in dark bedrooms in the lab. During scheduled wake, participants will remain awake in normal dim room light except during bright light sessions, when light will range from 5000 to 7000 lux. Study groups will differ by the light exposure they receive during the lab sessions. In the afternoon bright light (ABL) group, participants will be exposed to 3 h of bright light on 3 consecutive afternoons. On the first day (day 10), light boxes will be turned on 5 h after fixed wake-up time. Then, the start of the light exposure will move 1 h earlier each day. In the morning bright light (MBL) group, participants will be exposed to 3 consecutive mornings of 3 h of bright light. On the morning of day 11, the 3-h bright light exposure will begin 1 h before their stable wake-up time. In the morning + afternoon bright light (MBL + ABL) group, bright light will begin at the same times as the ABL and MBL groups and participants will received the same duration of bright light per day (3 h) as the ABL and MBL groups because the duration of each exposure will be 1.5 h instead of 3 h. Both bright light exposures will move 1 h earlier on subsequent days. In the room light control group, participants will complete the same 7-day lab session, except remain in dim room lighting. All participants will complete a final circadian phase assessment at the end of the 7-day lab session (day 13).
- Conditions
- Chronobiology, Light, Sleep, Circadian Rhythm, Adolescence
- Being tested
- Baseline Sleep Satiation and Phase Stabilization, Gradually Shifted Sleep
- Keywords
- Sleep, Circadian Rhythm, Adolescence
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Baseline Sleep Satiation and Phase StabilizationBehavioural
All participants will be assigned a 9-h sleep opportunity for the first week of the 2-week study. This will ensure that adolescents are not sleep restricted before living in the laboratory during the second week of the study. The 9-h sleep schedule will be individually timed from his/her averaged wake time (± 15 mins) before the study begins. Assigned bedtime will be 9 h before wake.
Gradually Shifted SleepBehavioural
For all participants, their assigned baseline sleep/wake schedule will gradually shift earlier over 3 days in the laboratory to facilitate the phase advance shift of the circadian system.
| Study group | Role | What they receive |
|---|---|---|
| Dim Room Light Control | Placebo comparator | Participants in the dim room light control group will not receive any bright light exposure. Receives: Behavioral: Baseline Sleep Satiation and Phase Stabilization; Behavioral: Gradually Shifted Sleep |
| Morning Bright Light Only (MBL) | Experimental | Participants in the morning bright light (MBL) group will receive a 3-h bright light exposure from 2 light boxes on 3 consecutive mornings in the laboratory. Bright light will be timed for each individual based on their baseline sleep schedule to shift the circadian timing system earlier ("phase advance"). Receives: Behavioral: Baseline Sleep Satiation and Phase Stabilization; Behavioral: Gradually Shifted Sleep |
| Afternoon Light Only (ABL) | Experimental | Participants in the afternoon bright light (ABL) group will receive a 3-h bright light exposure from 2 light boxes on 3 consecutive afternoons in the laboratory. Bright light will be timed for each individual based on their baseline sleep schedule to shift the circadian timing system earlier ("phase advance"). Receives: Behavioral: Baseline Sleep Satiation and Phase Stabilization; Behavioral: Gradually Shifted Sleep |
| Morning + Afternoon Light (MBL+ ABL) | Experimental | Participants in the morning bright light + afternoon bright light (MBL+ ABL) group will receive bright light from 2 light boxes on 3 consecutive days in the laboratory. The morning exposure will be 1.5 h and the afternoon exposure will be 1.5 h. Bright light exposures will be timed for each individual based on their baseline sleep schedule to shift the circadian timing system earlier ("phase advance"). Receives: Behavioral: Baseline Sleep Satiation and Phase Stabilization; Behavioral: Gradually Shifted Sleep |
What is being measured
The primary outcome is the main question the study is designed to answer.
Dim Light Melatonin Onset (DLMO) Phase Shift Change
Saliva sampling for the baseline DLMO will begin 6 hours before baseline bedtime and end 2 hours after baseline bedtime to capture the rise of endogenous melatonin. Sampling for the final DLMO will begin 7 hours before baseline bedtime and end 2 hours after baseline bedtime. Participants remain awake and seated in comfortable recliners in dim light (< 5 lux), except when they need to use the adjoining restroom (also < 5 lux). Saliva samples are collected every 30 minutes using Salivettes, The samples are immediately centrifuged and frozen, and later shipped on dry ice to SolidPhase, Inc. (Portland, ME), where they are analyzed for melatonin using direct radioimmunoassay (RIA). We compute the DLMO using a 4 pg/mL threshold; the time at which melatonin values surpass this threshold is the DLMO. Baseline - Final DLMO will define the phase shift change of the central circadian clock.
Measured: Change in DLMO phase from baseline (day 8) to final phase assessment (day 13)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Feb 2021
- Study start22 Aug 2022
- Primary completion18 May 2025
- Study completion18 May 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ChronobiologyStudies of the same condition, open and under way.
- 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
- Factorial
- Masking
- None (open label)
- Enrolment
- 84 participants (actual)
Sponsor and investigators
- Lead sponsor
- Rush University Medical Center
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04753190
- Sponsor's protocol ID
- R01HL151512
- Acronym
- ALT
- Status last verified
- Sep 2026
- First submitted
- 8 Feb 2021
- Last updated
- 15 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 15 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Adolescent Circadian Phase Shifts: Novel Time-of-day Targets for Bright Light
- ClinicalTrials.gov ID
- NCT04753190
- Acronym / sponsor ID
- ALT / R01HL151512
- Conditions
- Chronobiology, Light, Sleep, Circadian Rhythm, Adolescence
- Keywords
- Sleep, Circadian Rhythm, Adolescence
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 84 participants (actual)
- Lead sponsor
- Rush University Medical CenterUniversity, hospital or other
- Study start
- 22 Aug 2022 (actual)
- Primary completion
- 18 May 2025 (actual)
- Study completion
- 18 May 2025 (actual)
- First posted
- 15 Feb 2021 (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.
Chronic circadian misalignment and sleep restriction peak during late adolescence, and are associated with morning daytime sleepiness, poor academic performance, conduct problems, depressed mood, suicidal ideation, substance use, insulin resistance, and obesity. Bright light exposure from light boxes can shift rhythms earlier (phase advance) to facilitate earlier sleep onset and reduce morning circadian misalignment and the associated risks. To phase advance circadian rhythms, the investigators' PRCs showed that the ideal time to begin light exposure was slightly before wake-up time and light should be avoided around bedtime because this is when light produces maximum phase delay shifts. An unexpected finding from these results, however, was a second advancing region in the afternoon (~6 to 9 h after habitual wake-up time) suggesting that afternoon light may have more circadian phase advancing ability than traditionally thought. The overall goal of this mechanistic study is to follow-up on the unexpected PRC findings and test whether individually-timed afternoon light alone and in combination with morning bright light can shift circadian rhythms earlier in older adolescents. Four groups will be compared in a randomized parallel group design: afternoon bright light, morning bright light, morning + afternoon bright light, and a dim room light control. Adolescents will complete a 2-week protocol. After a baseline week with a stable sleep schedule, adolescents will live in the laboratory for 7 days. Sleep/dark and the time of bright light exposure will gradually shift earlier. Bright light (~5000 lux) will be timed individually based on his/her stable baseline sleep schedule. The first 3-h morning bright light exposure will begin 1 h before wake on the first morning. The first 3-h afternoon bright light exposure will begin 5 h after wake. The morning + afternoon exposures will begin at the same times, but each exposure will be 1.5 h so that a total of 3 h of bright light per day will be given to each group except the dim light control group. Phase shifts of the circadian clocks marked by the dim light melatonin onset (DLMO) is the main outcome. Investigators hypothesize that afternoon bright light will work synergistically with morning bright light to produce larger shifts than morning or afternoon bright light alone. These data could challenge the current understanding of how to use bright light to shift circadian rhythms earlier.
Detailed description
Participants will complete a 14-day protocol. On days 1-7, participants will sleep at home on a stable sleep schedule that requires 9 h of time in bed in the dark. This will ensure that participants are not sleep deprived before beginning the lab sessions. Wake time will be the average of the self-reported wake-up time (± 15 mins) before the study begins measured from pre-study sleep logs collected for a week or more. Bedtime will be 9 h before wake-up time. A device worn on the wrist that measures activity (actigraph), sleep diaries, and daily telephone messages will monitor compliance to the sleep schedule. Participants will visit the lab at least once during this week to download and review their data. If participants are not compliant to the sleep schedule, they will be dropped from the study.
On days 8-13, participants will live in the laboratory for seven days. On day 8, participants will arrive at the laboratory in the afternoon, and shortly after, will begin a baseline circadian phase assessment to determine baseline dim light melatonin onset (DLMO), a reliable marker of the circadian timing system. On day 9, participants will sleep on their stable 9-h sleep schedule in the laboratory. Their 9-h fixed sleep schedule will be shifted by 1 h per day over 3 days. Participants will sleep in dark bedrooms in the lab. During scheduled wake, participants will remain awake in normal dim room light except during bright light sessions, when light will range from 5000 to 7000 lux. Study groups will differ by the light exposure they receive during the lab sessions. In the afternoon bright light (ABL) group, participants will be exposed to 3 h of bright light on 3 consecutive afternoons. On the first day (day 10), light boxes will be turned on 5 h after fixed wake-up time. Then, the start of the light exposure will move 1 h earlier each day. In the morning bright light (MBL) group, participants will be exposed to 3 consecutive mornings of 3 h of bright light. On the morning of day 11, the 3-h bright light exposure will begin 1 h before their stable wake-up time. In the morning + afternoon bright light (MBL + ABL) group, bright light will begin at the same times as the ABL and MBL groups and participants will received the same duration of bright light per day (3 h) as the ABL and MBL groups because the duration of each exposure will be 1.5 h instead of 3 h. Both bright light exposures will move 1 h earlier on subsequent days. In the room light control group, participants will complete the same 7-day lab session, except remain in dim room lighting. All participants will complete a final circadian phase assessment at the end of the 7-day lab session (day 13).
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Factorial
- Masking
- None (open label)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Dim Room Light Control | Placebo comparator | Behavioral: Baseline Sleep Satiation and Phase Stabilization, Behavioral: Gradually Shifted SleepParticipants in the dim room light control group will not receive any bright light exposure. |
| Morning Bright Light Only (MBL) | Experimental | Behavioral: Baseline Sleep Satiation and Phase Stabilization, Behavioral: Gradually Shifted SleepParticipants in the morning bright light (MBL) group will receive a 3-h bright light exposure from 2 light boxes on 3 consecutive mornings in the laboratory. Bright light will be timed for each individual based on their baseline sleep schedule to shift the circadian timing system earlier ("phase advance"). |
| Afternoon Light Only (ABL) | Experimental | Behavioral: Baseline Sleep Satiation and Phase Stabilization, Behavioral: Gradually Shifted SleepParticipants in the afternoon bright light (ABL) group will receive a 3-h bright light exposure from 2 light boxes on 3 consecutive afternoons in the laboratory. Bright light will be timed for each individual based on their baseline sleep schedule to shift the circadian timing system earlier ("phase advance"). |
| Morning + Afternoon Light (MBL+ ABL) | Experimental | Behavioral: Baseline Sleep Satiation and Phase Stabilization, Behavioral: Gradually Shifted SleepParticipants in the morning bright light + afternoon bright light (MBL+ ABL) group will receive bright light from 2 light boxes on 3 consecutive days in the laboratory. The morning exposure will be 1.5 h and the afternoon exposure will be 1.5 h. Bright light exposures will be timed for each individual based on their baseline sleep schedule to shift the circadian timing system earlier ("phase advance"). |
Who may qualify
- Ages
- 18 to 20 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (2 listed)
- between 18-20 years old
- lives in or near Chicago, IL
Key exclusion criteria (0 listed)
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 |
|---|---|---|
| Baseline Sleep Satiation and Phase StabilizationAll participants will be assigned a 9-h sleep opportunity for the first week of the 2-week study. This will ensure that adolescents are not sleep restricted before living in the laboratory during the second week of the study. The 9-h sleep schedule will be individually timed from his/her averaged wake time (± 15 mins) before the study begins. Assigned bedtime will be 9 h before wake. | Behavioural | Afternoon Light Only (ABL), Dim Room Light Control, Morning + Afternoon Light (MBL+ ABL), Morning Bright Light Only (MBL) |
| Gradually Shifted SleepFor all participants, their assigned baseline sleep/wake schedule will gradually shift earlier over 3 days in the laboratory to facilitate the phase advance shift of the circadian system. | Behavioural | Afternoon Light Only (ABL), Dim Room Light Control, Morning + Afternoon Light (MBL+ ABL), Morning Bright Light Only (MBL) |
Primary outcome
Dim Light Melatonin Onset (DLMO) Phase Shift Change
Time frame: Change in DLMO phase from baseline (day 8) to final phase assessment (day 13)
Saliva sampling for the baseline DLMO will begin 6 hours before baseline bedtime and end 2 hours after baseline bedtime to capture the rise of endogenous melatonin. Sampling for the final DLMO will begin 7 hours before baseline bedtime and end 2 hours after baseline bedtime. Participants remain awake and seated in comfortable recliners in dim light (< 5 lux), except when they need to use the adjoining restroom (also < 5 lux). Saliva samples are collected every 30 minutes using Salivettes, The samples are immediately centrifuged and frozen, and later shipped on dry ice to SolidPhase, Inc. (Portland, ME), where they are analyzed for melatonin using direct radioimmunoassay (RIA). We compute the DLMO using a 4 pg/mL threshold; the time at which melatonin values surpass this threshold is the DLMO. Baseline - Final DLMO will define the phase shift change of the central circadian clock.
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 15 Sep 2026.
Related trials for Chronobiology
Not yet recruitingEarly Phase 1
reALIGNing Circadian Rhythm and Promoting Sleep in the Intensive Care Unit
Sleep, Circadian Dysregulation
Recruiting
Mind After Midnight
Suicidal Ideation, Circadian Rhythm Disorders
Active, not recruitingObservational study
Evaluation of the Effect of Seasonality on Biological Age in Adults
Aging, Aging, Biological
Recruiting
Early Pregnancy Lifestyle and Glucose Patterns: A Substudy of TOFFFY
Continuous Glucose Monitoring, Diabetes, Gestational
RecruitingObservational study
Body Clocks - Coordination of Peripheral and Central Oscillators
Circadian Dysregulation
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 Baseline Sleep Satiation and Phase Stabilization and Gradually Shifted Sleep in people with Chronobiology and Light, run by Rush University Medical Center 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 2 inclusion and 0 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 15 Sep 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?
Dim Light Melatonin Onset (DLMO) Phase Shift Change (time frame: Change in DLMO phase from baseline (day 8) to final phase assessment (day 13)). 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 15 Sep 2026; AzTrials last refreshed its copy on 28 Oct 2026.