SleepBLIGHTNCT07685262
Morning Bright Light Therapy and Daytime Functioning in University Students
A study testing Bright light therapy (10,000 lux light box) in people with Sleep and Circadian Rhythm, run by The Hong Kong Polytechnic University at 1 site in Hong Kong.
Trial summary
This study tests whether a week of morning bright light therapy changes how well healthy young adults sleep and how alert, positive, and mentally sharp they feel during the day. Morning light is the body's main signal for keeping its internal clock and sleep-wake timing on track. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Sleep, Circadian Rhythm, Daytime Sleepiness
- What is being tested?
- Bright light therapy (10,000 lux light box)
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 153 participants
- Where
- 1 siteHong Kong
- Study dates
- 1 May 2024to 30 Jun 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Enrolled university student
- Aged 18 years or older
- Generally healthy, with no diagnosed sleep disorder (sleep quality screened using the Pittsburgh Sleep Quality Index)
- Residing in shared student housing
Who cannot join
- Diagnosed insomnia or other diagnosed sleep disorder
- Other medical, psychiatric, or neurological condition that could affect sleep, mood, or cognition
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Hong Kong1 site, 1 recruiting
- Recruiting
The Hong Kong Polytechnic University
Hung Hom
About this study
Official title: Effects of Morning Bright Light Therapy on Sleep, Alertness, Mood, and Cognition in Healthy University Students: A Randomized Crossover Trial
This study tests whether a week of morning bright light therapy changes how well healthy young adults sleep and how alert, positive, and mentally sharp they feel during the day.
Morning light is the body's main signal for keeping its internal clock and sleep-wake timing on track. Many university students keep irregular hours and spend most of the day indoors, where light is far dimmer than daylight. This study asks whether adding a short, bright morning light session can help.
Read more
Each participant takes part for two weeks. For one week they use a bright light box for 30 minutes each morning, shortly after waking; for the other week they keep their usual lighting. The order of the two weeks is decided at random, and each person serves as their own comparison.
Throughout both weeks, sleep is tracked with a wrist-worn Fitbit and a short daily diary. Participants also rate their sleepiness and mood, complete brief computer-based attention and memory tasks, and take part in a short interview at the end about their experience.
The study compares the bright-light week with the usual-light week to see whether morning bright light improves sleep regularity and efficiency, reduces daytime sleepiness, lifts mood, or affects thinking performance. The trial is being conducted in waves; a first wave has completed and a second wave is planned, pending additional funding.
Read the detailed description
Background and rationale: Morning light is the principal entraining signal for the human circadian system, acting through melanopsin-containing intrinsically photosensitive retinal ganglion cells that project to the suprachiasmatic nucleus. University students frequently experience irregular sleep-wake schedules and limited daytime light exposure, particularly in cooling-dominant subtropical buildings where occupants keep blinds drawn. Bright light therapy (BLT) is an established treatment for circadian and affective disorders, but its effects on sleep regularity, daytime alertness, mood, and objective cognition in healthy students are less well characterized. This trial evaluates a brief, self-administered morning BLT regimen using a within-subject crossover design.
Design: Single-center, randomized, within-subject (crossover) trial. Each participant completes two consecutive one-week conditions-morning BLT and usual-light control-in counterbalanced order with no washout period. Allocation to condition order (sequence) is randomized, and each participant serves as their own control; all crossover models include condition, period (week), and sequence terms.
Setting and population: Healthy university students residing in shared student housing in Hong Kong. Eligibility is restricted to generally healthy young adults without a diagnosed sleep disorder; sleep quality is screened (Pittsburgh Sleep Quality Index), and individuals with diagnosed insomnia or other relevant conditions are excluded.
Intervention: During the BLT week, participants self-administer a 30-minute session of 10,000 lux (photopic) bright light approximately 30 minutes after waking, using a standard light therapy lamp positioned per manufacturer guidance. The stimulus is characterized in melanopic units (melanopic equivalent daylight illuminance ≈ 8,989 lux). During the control week, participants maintain their usual indoor lighting and morning routine without the lamp.
Assessments: Sleep is monitored continuously with a wrist-worn Fitbit and a daily diary throughout both weeks. Daytime sleepiness and alertness are rated at fixed times of day (Karolinska and Stanford Sleepiness Scales). Mood and affect are assessed with the Positive and Negative Affect Schedule and the Profile of Mood States. A computer-based cognitive battery (Stroop, Flanker, Corsi block-tapping, verbal span) is administered at the end of each condition week. Post-trial semi-structured interviews capture subjective experience and acceptability.
Outcome structure: A small, a priori primary confirmatory outcome family-defined in the approved study protocol on the basis of hypothesized domains rather than observed effects-covers daytime sleepiness, sleep regularity, positive affect, and cognition; remaining measures are secondary or exploratory. Formal outcome-measure definitions are provided in the Outcome Measures module.
Statistical analysis: Outcomes are analyzed with linear mixed-effects models of the form outcome ~ condition + period + sequence + (1 | participant), estimated by REML with Satterthwaite degrees of freedom. Multiplicity is controlled with Holm correction across the primary outcome family. Paired within-person effect sizes (Cohen's dz) accompany model-based estimates, and sensitivity analyses examine period, sequence, and carryover effects.
Conduct in waves: The trial is being conducted in waves. A first wave (33 participants) has completed data collection; a second wave is planned and will commence pending additional funding, so recruitment is currently inactive.
- Conditions
- Sleep, Circadian Rhythm, Daytime Sleepiness, Mood, Cognition, Healthy Volunteers
- Being tested
- Bright light therapy (10,000 lux light box)
- Keywords
- Bright light therapy, Melanopic illuminance, Morning light exposure, Sleep regularity, Sleep efficiency, Daytime alertness, Crossover trial, University students, Wearable sleep tracking, Karolinska Sleepiness Scale
- Medical subject headings
- Disorders of Excessive Somnolence
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Bright light therapy (10,000 lux light box)Device
Self-administered 30-minute session of 10,000 lux (photopic) bright light each morning, approximately 30 minutes after waking, for one week, using a standard 10,000-lux light therapy lamp positioned per manufacturer guidance. Stimulus characterized in melanopic units (melanopic equivalent daylight illuminance ≈ 8,989 lux).
| Study group | Role | What they receive |
|---|---|---|
| Morning Bright Light Therapy | Experimental | During this one-week condition, participants self-administer a 30-minute session of 10,000 lux bright light (melanopic equivalent daylight illuminance ≈ 8,989 lux) each morning, approximately 30 minutes after waking, using a standard light therapy lamp positioned per manufacturer guidance. Receives: Device: Bright light therapy (10,000 lux light box) |
| Usual Light (Control) | No intervention | During this one-week condition, participants maintain their usual indoor lighting and morning routine without the light therapy lamp. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Sleep regularity
Regularity of sleep timing derived from wrist-worn Fitbit actigraphy and a daily sleep diary (e.g., day-to-day variability in sleep onset and offset). Condition-week values are compared between the bright-light week and the usual-light week.
Measured: Recorded continuously across each 1-week condition (bright-light week and usual-light week).
Daytime sleepiness (Karolinska Sleepiness Scale)
Subjective daytime sleepiness rated on the 9-point Karolinska Sleepiness Scale (KSS) at fixed times of day. Condition-week values are compared between the bright-light week and the usual-light week.
Measured: Assessed daily at fixed times across each 1-week condition (bright-light week and usual-light week).
Positive affect (PANAS Positive Affect subscale)
Positive affect measured with the Positive and Negative Affect Schedule (PANAS) positive-affect subscale. Condition-week scores are compared between the bright-light week and the usual-light week.
Measured: End of each 1-week condition (bright-light week and usual-light week).
Cognitive performance (computer-based battery)
Objective cognitive performance on a computer-based battery (Stroop, Flanker, Corsi block-tapping, and verbal span tasks). Condition-week performance is compared between the bright-light week and the usual-light week.
Measured: End of each 1-week condition (bright-light week and usual-light week).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Jul 2026
- Study start1 May 2024
- Primary completion30 Jun 2028 (estimated)
- Study completion30 Jun 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for SleepStudies of the same condition, open and under way.
- More trials run by The Hong Kong Polytechnic UniversityThe 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
- Crossover
- Model description
- Randomized within-subject crossover trial. Each participant completes two consecutive 1-week conditions - morning bright light therapy and usual-light control - in counterbalanced (randomized) order with no washout period. Each participant serves as their own control; mixed-effects analyses include condition, period, and sequence terms.
- Masking
- None (open label)
- Enrolment
- 153 participants (estimated)
Sponsor and investigators
- Lead sponsor
- The Hong Kong Polytechnic University
- Sponsor type
- University, hospital or other
- Collaborators
- Northumbria University
- Responsible party
- Principal investigator, Dr YU Cehao, The Hong Kong Polytechnic University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07685262
- Sponsor's protocol ID
- HSEARS20240430005
- Other IDs
- P0050050
- Acronym
- BLIGHT
- Status last verified
- Jun 2026
- First submitted
- 29 Jun 2026
- Last updated
- 6 Jul 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 6 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Morning Bright Light Therapy on Sleep, Alertness, Mood, and Cognition in Healthy University Students: A Randomized Crossover Trial
- ClinicalTrials.gov ID
- NCT07685262
- Acronym / sponsor ID
- BLIGHT / HSEARS20240430005
- Conditions
- Sleep, Circadian Rhythm, Daytime Sleepiness, Mood, Cognition, Healthy Volunteers
- Keywords
- Bright light therapy, Melanopic illuminance, Morning light exposure, Sleep regularity, Sleep efficiency, Daytime alertness, Crossover trial, University students
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 153 participants (estimated)
- Lead sponsor
- The Hong Kong Polytechnic UniversityUniversity, hospital or other
- Collaborators
- Northumbria University
- Study start
- 1 May 2024 (actual)
- Primary completion
- 30 Jun 2028 (estimated)
- Study completion
- 30 Jun 2028 (estimated)
- First posted
- 6 Jul 2026 (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.
This study tests whether a week of morning bright light therapy changes how well healthy young adults sleep and how alert, positive, and mentally sharp they feel during the day.
Morning light is the body's main signal for keeping its internal clock and sleep-wake timing on track. Many university students keep irregular hours and spend most of the day indoors, where light is far dimmer than daylight. This study asks whether adding a short, bright morning light session can help.
Each participant takes part for two weeks. For one week they use a bright light box for 30 minutes each morning, shortly after waking; for the other week they keep their usual lighting. The order of the two weeks is decided at random, and each person serves as their own comparison.
Throughout both weeks, sleep is tracked with a wrist-worn Fitbit and a short daily diary. Participants also rate their sleepiness and mood, complete brief computer-based attention and memory tasks, and take part in a short interview at the end about their experience.
The study compares the bright-light week with the usual-light week to see whether morning bright light improves sleep regularity and efficiency, reduces daytime sleepiness, lifts mood, or affects thinking performance. The trial is being conducted in waves; a first wave has completed and a second wave is planned, pending additional funding.
Detailed description
Background and rationale: Morning light is the principal entraining signal for the human circadian system, acting through melanopsin-containing intrinsically photosensitive retinal ganglion cells that project to the suprachiasmatic nucleus. University students frequently experience irregular sleep-wake schedules and limited daytime light exposure, particularly in cooling-dominant subtropical buildings where occupants keep blinds drawn. Bright light therapy (BLT) is an established treatment for circadian and affective disorders, but its effects on sleep regularity, daytime alertness, mood, and objective cognition in healthy students are less well characterized. This trial evaluates a brief, self-administered morning BLT regimen using a within-subject crossover design.
Design: Single-center, randomized, within-subject (crossover) trial. Each participant completes two consecutive one-week conditions-morning BLT and usual-light control-in counterbalanced order with no washout period. Allocation to condition order (sequence) is randomized, and each participant serves as their own control; all crossover models include condition, period (week), and sequence terms.
Setting and population: Healthy university students residing in shared student housing in Hong Kong. Eligibility is restricted to generally healthy young adults without a diagnosed sleep disorder; sleep quality is screened (Pittsburgh Sleep Quality Index), and individuals with diagnosed insomnia or other relevant conditions are excluded.
Intervention: During the BLT week, participants self-administer a 30-minute session of 10,000 lux (photopic) bright light approximately 30 minutes after waking, using a standard light therapy lamp positioned per manufacturer guidance. The stimulus is characterized in melanopic units (melanopic equivalent daylight illuminance ≈ 8,989 lux). During the control week, participants maintain their usual indoor lighting and morning routine without the lamp.
Assessments: Sleep is monitored continuously with a wrist-worn Fitbit and a daily diary throughout both weeks. Daytime sleepiness and alertness are rated at fixed times of day (Karolinska and Stanford Sleepiness Scales). Mood and affect are assessed with the Positive and Negative Affect Schedule and the Profile of Mood States. A computer-based cognitive battery (Stroop, Flanker, Corsi block-tapping, verbal span) is administered at the end of each condition week. Post-trial semi-structured interviews capture subjective experience and acceptability.
Outcome structure: A small, a priori primary confirmatory outcome family-defined in the approved study protocol on the basis of hypothesized domains rather than observed effects-covers daytime sleepiness, sleep regularity, positive affect, and cognition; remaining measures are secondary or exploratory. Formal outcome-measure definitions are provided in the Outcome Measures module.
Statistical analysis: Outcomes are analyzed with linear mixed-effects models of the form outcome ~ condition + period + sequence + (1 | participant), estimated by REML with Satterthwaite degrees of freedom. Multiplicity is controlled with Holm correction across the primary outcome family. Paired within-person effect sizes (Cohen's dz) accompany model-based estimates, and sensitivity analyses examine period, sequence, and carryover effects.
Conduct in waves: The trial is being conducted in waves. A first wave (33 participants) has completed data collection; a second wave is planned and will commence pending additional funding, so recruitment is currently inactive.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Randomized within-subject crossover trial. Each participant completes two consecutive 1-week conditions - morning bright light therapy and usual-light control - in counterbalanced (randomized) order with no washout period. Each participant serves as their own control; mixed-effects analyses include condition, period, and sequence terms.
| Arm | Type | Receives |
|---|---|---|
| Morning Bright Light Therapy | Experimental | Device: Bright light therapy (10,000 lux light box)During this one-week condition, participants self-administer a 30-minute session of 10,000 lux bright light (melanopic equivalent daylight illuminance ≈ 8,989 lux) each morning, approximately 30 minutes after waking, using a standard light therapy lamp positioned per manufacturer guidance. |
| Usual Light (Control) | No intervention | –During this one-week condition, participants maintain their usual indoor lighting and morning routine without the light therapy lamp. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Enrolled university student
- Aged 18 years or older
- Generally healthy, with no diagnosed sleep disorder (sleep quality screened using the Pittsburgh Sleep Quality Index)
- Residing in shared student housing
Key exclusion criteria (2 listed)
- Diagnosed insomnia or other diagnosed sleep disorder
- Other medical, psychiatric, or neurological condition that could affect sleep, mood, or cognition
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 light therapy (10,000 lux light box)Self-administered 30-minute session of 10,000 lux (photopic) bright light each morning, approximately 30 minutes after waking, for one week, using a standard 10,000-lux light therapy lamp positioned per manufacturer guidance. Stimulus characterized in melanopic units (melanopic equivalent daylight illuminance ≈ 8,989 lux). | Device | Morning Bright Light Therapy |
Primary outcome
Sleep regularity
Time frame: Recorded continuously across each 1-week condition (bright-light week and usual-light week).
Regularity of sleep timing derived from wrist-worn Fitbit actigraphy and a daily sleep diary (e.g., day-to-day variability in sleep onset and offset). Condition-week values are compared between the bright-light week and the usual-light week.
Daytime sleepiness (Karolinska Sleepiness Scale)
Time frame: Assessed daily at fixed times across each 1-week condition (bright-light week and usual-light week).
Subjective daytime sleepiness rated on the 9-point Karolinska Sleepiness Scale (KSS) at fixed times of day. Condition-week values are compared between the bright-light week and the usual-light week.
Positive affect (PANAS Positive Affect subscale)
Time frame: End of each 1-week condition (bright-light week and usual-light week).
Positive affect measured with the Positive and Negative Affect Schedule (PANAS) positive-affect subscale. Condition-week scores are compared between the bright-light week and the usual-light week.
Cognitive performance (computer-based battery)
Time frame: End of each 1-week condition (bright-light week and usual-light week).
Objective cognitive performance on a computer-based battery (Stroop, Flanker, Corsi block-tapping, and verbal span tasks). Condition-week performance is compared between the bright-light week and the usual-light week.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Jul 2026.
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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.
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 therapy (10,000 lux light box) in people with Sleep and Circadian Rhythm, run by The Hong Kong Polytechnic University at 1 site in Hong Kong.
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 4 inclusion and 2 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: looking for participants now, as of the sponsor's last update on 6 Jul 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 Hong Kong. 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. 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Cehao Yu, PhD (+852 3400 3012, cehao.yu@polyu.edu.hk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Sleep regularity (time frame: Recorded continuously across each 1-week condition (bright-light week and usual-light week).). The study lists 4 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 Jul 2026.