Psychological StressBLISSNCT04900675
Bright Light Intervention to Reduce Students' Stress
A study testing Bright light intervention in people with Psychological Stress and Physiological Stress, run by Universitaet Innsbruck at 1 site in Austria.
Trial summary
Increased stress levels are a significant problem for many students and represent a risk factor for impaired mental and physical health as well as academic performance. Stress levels are particularly high during the preparation phase for major exams. Read more about this study
- Who is it for?
- Ages 18 to 35 yearsHealthy volunteers can take part
- Conditions the study is for
- Psychological Stress, Physiological Stress, Sleep Disorders, Circadian Rhythm
- What is being tested?
- Bright light intervention
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 125 participants
- Where
- 1 siteAustria
- Study dates
- 1 Oct 2020to 31 Oct 2024
- 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 35 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- students from the faculty of medicine, pharmacy, and law
- major exam at least 5 weeks ahead
- major depressive disorder (PHQ-9): Score > 4
- possession of smartphone and data plan
Who cannot join
- suicidal ideation (BDI, Item i): Rating > 1
- seasonal affective disorder (PIDS-A): Score > 11
- taking medication which increases photo-sensitivity
- taking medication to increase cognitive performance
- starting or changing pharmacotherapy for affective disorders and anxiety disorders within the last two weeks
- changing of all kinds of medication within the last two weeks
Show all 10Show fewer
- headache (PHQ-D, Item f): Rating "severly impaired"
- increased light sensitivity: Item "Wearing sunglasses outside on sunny days" is answered with 'often' or 'very often'
- currently undergoing psychotherapeutic treatment
- the presence of an eye disease for which light therapy is contraindicated
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Effects of Bright Morning Light Exposure on Students' Stress, Mood, Anxiety, Sleep and, Circadian Rest-activity Cycle
Increased stress levels are a significant problem for many students and represent a risk factor for impaired mental and physical health as well as academic performance. Stress levels are particularly high during the preparation phase for major exams.
There is good evidence that light therapy is an effective treatment option to improve mood in affective disorders.
The present study aims at investigating the psychophysiological effects of a 3-week morning bright light exposure in reducing stress and stress-related problems in students preparing for major exams.
Read the detailed description
Increased students' stress represents a significant risk factor for impaired mental and physical health as well as academic performance. The World Mental Health Survey (WHO) reports a 12-month prevalence of mental illness of 20.3% among students, with anxiety disorders (14.7%), affective disorders (9.9%), and substance abuse (6.7%) being particularly prominent. Moreover, six out of 10 students suffer from impaired sleep quality.
Offering an effective treatment for stress-related symptoms in students is a challenge. In situations of intense stress, conventional methods such as relaxation and mindfulness-based programs often fail because of poor prior practice. Only a few students apply cognitive behavioral interventions. Although medication might decrease stress symptoms within days, the side effects of drugs cannot be ignored. Therefore, there is a need for effective and efficient treatment of acute stress symptoms in students.
Bright light therapy is an effective treatment for several mental disorders, e.g. affective disorders and sleep disorders. There is some evidence, that exposure to bright light may even reduce stress in patients with burnout symptoms. Thus, exposure to bright light may be a promising new option to reduce academic stress and improve mood and sleep parameters.
In the present study, a large-area desk lamp, which emits diffuse light and is controllable in its luminance and correlated color temperature is used. Study participants are randomly assigned to one of three study arms: (i) exposure to polychromatic light of 5,000 lux and 5,300 Kelvin, (ii) exposure to polychromatic light of 50 lux and 2,200 Kelvin, or (iii) no light intervention. Data collection takes place in winter periods.
- Being tested
- Bright light intervention, Reddish placebo light
- Keywords
- stress, light therapy
- Medical subject headings
- Stress, Psychological, Sleep Disorders, Circadian Rhythm
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Bright light interventionOther
Exposure with 5,000 lux at eye level for one hour and a Correlated Color Temperature of 5,300 Kelvin every morning for three weeks.
Reddish placebo lightOther
Exposure with 50 lux at eye level for one hour and a Correlated Color Temperature of 2,200 Kelvin every morning for three weeks.
| Study group | Role | What they receive |
|---|---|---|
| bright white light intervention | Experimental | exposure to 5,000 lux with polychromatic white light with 5,300 Kelvin at eye level; light exposure starts immediately after awakening; light exposure takes place on weekdays (Monday till Friday) over a period of 3 weeks Receives: Other: Bright light intervention |
| dim reddish light intervention | Placebo comparator | exposure to 50 lux with polychromatic reddish light with 2,200 Kelvin at eye level; light exposure starts immediately after awakening; light exposure takes place on weekdays (Monday till Friday) over a period of 3 weeks Receives: Other: Reddish placebo light |
| no light intervention | No intervention | no light intervention takes place in the morning; the study participants follow their natural rhythm of life |
What is being measured
The primary outcome is the main question the study is designed to answer.
subjective stress level - baseline/post
Perceived Stress Scale (PSS-10); scale: PSS-10 sum score; range:0 - 40; higher scores mean a higher subjective stress level
Measured: Change from baseline PSS-10 sum score at the end of week 3
subjective stress level - baseline/post
Perceived Stress Questionnaire (PSQ-20); scale: PSQ-20 sum score; range: 20 - 80; higher scores mean a higher subjective stress level
Measured: Change from baseline PSQ-20 sum score at the end of week 3
subjective stress level - on weekdays
Perceived Stress Questionnaire (PSQ-20); scale: PSQ-20 sum score; range: 20 - 80; higher scores mean a higher subjective stress level
Measured: Change of daily PSQ-20 sum score at each weekday during the light intervention period up to 3 weeks
Secondary outcomes (12)
anxiety
State-Trait Anxiety Inventory (STAI - form Y) - 20 trait items; scale: STAI-trait sum score; range: 20 - 80; higher scores mean a higher subjective anxiety level
Measured: Change from baseline STAI-trait sum score at the end of week 3
mood
Center for Epidemiologic Studies Depression Scale (CES--D); scale: CES-D sum score; range: 0 - 60; higher scores mean a higher subjective depression level
Measured: Change from baseline CES-D sum score at the end of week 3
sleep quality
Pittsburgh Sleep Quality Index (PSQI); scale: global PSQI score; range: 0 - 21; higher scores mean a lower subjective sleep quality
Measured: Change from baseline global PSQI score at the end of week 3
sleep quality - total sleep time
Wrist actimetry to measure daily total sleep time (TST); scale: sleep duration; range: >0 (minutes); higher TST means longer sleep period
Measured: Change of TST at each night during the light intervention period up to 3 weeks
sleep quality - sleep onset latency
Wrist actimetry to measure daily sleep onset latency (SOL); scale: duration to fall asleep; range: >0 (minutes); higher SOL means longer period to fall asleep
Measured: change of SOL at each night during the light intervention period up to 3 weeks
sleep quality - wake after sleep onset
Wrist actimetry to measure daily wake after sleep onset (WASO); scale: duration of being awake during sleep period; range: greater than or equal to 0 (minutes); higher WASO means longer wake periods after sleep onset
Measured: change of WASO at each night during the light intervention period up to 3 weeks
sleep quality - sleep efficiency
Wrist actimetry to measure daily sleep efficiency (SE); scale: percentage; range: 0 - 100; higher SE means a higher undisturbed sleep
Measured: change of SE at each night during the light intervention period up to 3 weeks
circadian rest/activity rhythm - interdaily stability
Circadian rest-activity cycle parameter interdaily stability (IS) derived from weekly wrist actimetry data; scale: real number; range: 0 -1; higher IS means a higher stability in daily rest-activity cycles
Measured: change of IV at each of the three light intervention weeks up to 3 weeks
circadian rest/activity rhythm - intradaily variability
Circadian rest-activity cycle parameter intradaily variability (IV) derived from averaged wrist actimetry data over a period of 1 week; scale: real number; range: 0 - 2; higher IV means a higher variability in 24-h rest-activity cycle
Measured: change of IS at each of the three light intervention weeks up to 3 weeks
physiological stress reaction
cortisol level measured from hair sample; scale: real number (pg/mg); range: >0; higher hair cortisol level means higher physiological stress
Measured: Change from baseline hair cortisol level at the end of week 3
adverse effects - short-term
astenopic complaints measured with 12 items; scale: sum score; range: 10 - 60; higher sum score means more astenopic complaints
Measured: day 5
adverse effects - long-term
astenopic complaints scale measured with 12 items: sum score; range: 10 - 60; higher sum score means more astenopic complaints
Measured: day 15
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 May 2021
- Study start1 Oct 2020
- Primary completion31 Mar 2024
- Study completion31 Oct 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Psychological StressStudies 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
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- placebo-controlled, randomized trial
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 125 participants (actual)
Sponsor and investigators
- Lead sponsor
- Universitaet Innsbruck
- Sponsor type
- University, hospital or other
- Collaborators
- Bartenbach GmbH
- Responsible party
- Principal investigator, Markus Canazei, Universitaet Innsbruck
- Investigators
- Markus Canazei, PhD, Principal investigator, University of Innsbruck, Austria
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04900675
- Sponsor's protocol ID
- 878649
- Acronym
- BLISS
- Status last verified
- Dec 2024
- First submitted
- 29 Apr 2021
- Last updated
- 26 Jun 2025
- 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 26 Jun 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Bright Morning Light Exposure on Students' Stress, Mood, Anxiety, Sleep and, Circadian Rest-activity Cycle
- ClinicalTrials.gov ID
- NCT04900675
- Acronym / sponsor ID
- BLISS / 878649
- Keywords
- stress, light therapy
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 125 participants (actual)
- Lead sponsor
- Universitaet InnsbruckUniversity, hospital or other
- Collaborators
- Bartenbach GmbH
- Study start
- 1 Oct 2020 (actual)
- Primary completion
- 31 Mar 2024 (actual)
- Study completion
- 31 Oct 2024 (actual)
- First posted
- 25 May 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.
Increased stress levels are a significant problem for many students and represent a risk factor for impaired mental and physical health as well as academic performance. Stress levels are particularly high during the preparation phase for major exams.
There is good evidence that light therapy is an effective treatment option to improve mood in affective disorders.
The present study aims at investigating the psychophysiological effects of a 3-week morning bright light exposure in reducing stress and stress-related problems in students preparing for major exams.
Detailed description
Increased students' stress represents a significant risk factor for impaired mental and physical health as well as academic performance. The World Mental Health Survey (WHO) reports a 12-month prevalence of mental illness of 20.3% among students, with anxiety disorders (14.7%), affective disorders (9.9%), and substance abuse (6.7%) being particularly prominent. Moreover, six out of 10 students suffer from impaired sleep quality.
Offering an effective treatment for stress-related symptoms in students is a challenge. In situations of intense stress, conventional methods such as relaxation and mindfulness-based programs often fail because of poor prior practice. Only a few students apply cognitive behavioral interventions. Although medication might decrease stress symptoms within days, the side effects of drugs cannot be ignored. Therefore, there is a need for effective and efficient treatment of acute stress symptoms in students.
Bright light therapy is an effective treatment for several mental disorders, e.g. affective disorders and sleep disorders. There is some evidence, that exposure to bright light may even reduce stress in patients with burnout symptoms. Thus, exposure to bright light may be a promising new option to reduce academic stress and improve mood and sleep parameters.
In the present study, a large-area desk lamp, which emits diffuse light and is controllable in its luminance and correlated color temperature is used. Study participants are randomly assigned to one of three study arms: (i) exposure to polychromatic light of 5,000 lux and 5,300 Kelvin, (ii) exposure to polychromatic light of 50 lux and 2,200 Kelvin, or (iii) no light intervention. Data collection takes place in winter periods.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 3
- Model description
- placebo-controlled, randomized trial
| Arm | Type | Receives |
|---|---|---|
| bright white light intervention | Experimental | Other: Bright light interventionexposure to 5,000 lux with polychromatic white light with 5,300 Kelvin at eye level; light exposure starts immediately after awakening; light exposure takes place on weekdays (Monday till Friday) over a period of 3 weeks |
| dim reddish light intervention | Placebo comparator | Other: Reddish placebo lightexposure to 50 lux with polychromatic reddish light with 2,200 Kelvin at eye level; light exposure starts immediately after awakening; light exposure takes place on weekdays (Monday till Friday) over a period of 3 weeks |
| no light intervention | No intervention | –no light intervention takes place in the morning; the study participants follow their natural rhythm of life |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- students from the faculty of medicine, pharmacy, and law
- major exam at least 5 weeks ahead
- major depressive disorder (PHQ-9): Score > 4
- possession of smartphone and data plan
Key exclusion criteria (10 listed)
- suicidal ideation (BDI, Item i): Rating > 1
- seasonal affective disorder (PIDS-A): Score > 11
- taking medication which increases photo-sensitivity
- taking medication to increase cognitive performance
- starting or changing pharmacotherapy for affective disorders and anxiety disorders within the last two weeks
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 interventionExposure with 5,000 lux at eye level for one hour and a Correlated Color Temperature of 5,300 Kelvin every morning for three weeks. | Other | bright white light intervention |
| Reddish placebo lightExposure with 50 lux at eye level for one hour and a Correlated Color Temperature of 2,200 Kelvin every morning for three weeks. | Other | dim reddish light intervention |
Primary outcome
subjective stress level - baseline/post
Time frame: Change from baseline PSS-10 sum score at the end of week 3
Perceived Stress Scale (PSS-10); scale: PSS-10 sum score; range:0 - 40; higher scores mean a higher subjective stress level
subjective stress level - baseline/post
Time frame: Change from baseline PSQ-20 sum score at the end of week 3
Perceived Stress Questionnaire (PSQ-20); scale: PSQ-20 sum score; range: 20 - 80; higher scores mean a higher subjective stress level
subjective stress level - on weekdays
Time frame: Change of daily PSQ-20 sum score at each weekday during the light intervention period up to 3 weeks
Perceived Stress Questionnaire (PSQ-20); scale: PSQ-20 sum score; range: 20 - 80; higher scores mean a higher subjective stress level
12 secondary outcomes
anxiety
Time frame: Change from baseline STAI-trait sum score at the end of week 3
mood
Time frame: Change from baseline CES-D sum score at the end of week 3
sleep quality
Time frame: Change from baseline global PSQI score at the end of week 3
sleep quality - total sleep time
Time frame: Change of TST at each night during the light intervention period up to 3 weeks
sleep quality - sleep onset latency
Time frame: change of SOL at each night during the light intervention period up to 3 weeks
sleep quality - wake after sleep onset
Time frame: change of WASO at each night during the light intervention period up to 3 weeks
sleep quality - sleep efficiency
Time frame: change of SE at each night during the light intervention period up to 3 weeks
circadian rest/activity rhythm - interdaily stability
Time frame: change of IV at each of the three light intervention weeks up to 3 weeks
circadian rest/activity rhythm - intradaily variability
Time frame: change of IS at each of the three light intervention weeks up to 3 weeks
physiological stress reaction
Time frame: Change from baseline hair cortisol level at the end of week 3
adverse effects - short-term
Time frame: day 5
adverse effects - long-term
Time frame: day 15
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 26 Jun 2025.
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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. This study is not recruiting at the moment.
Markus Canazei, PhD principal investigator
University of Innsbruck, Austria
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 intervention in people with Psychological Stress and Physiological Stress, run by Universitaet Innsbruck at 1 site in Austria.
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 10 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 26 Jun 2025. 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 Austria. 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?
subjective stress level - baseline/post (time frame: Change from baseline PSS-10 sum score at the end of week 3). 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 26 Jun 2025.