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Completed

NCT Number: NCT04900675

Bright Light Intervention to Reduce Students' Stress

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.

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Key information

Conditions

Psychological Stress Behavior Behavioral Symptoms Chronobiology Disorders Dyssomnias Mental Disorders Nervous System Diseases Occupational Diseases Physiological Stress Sleep Disorders, Circadian Rhythm Sleep Wake Disorders Stress, Psychological

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Innsbruck

Innsbruck, Tyrol, 6020, Austria

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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
  • 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

Treatment and study plan

Bright light intervention

Other

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 light

Other

Exposure with 50 lux at eye level for one hour and a Correlated Color Temperature of 2,200 Kelvin every morning for three weeks.

Primary outcomes

  1. 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

  2. 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

  3. 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

Secondary outcomes

  1. anxiety

    Time frame: Change from baseline STAI-trait sum score at the end of week 3

    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

  2. mood

    Time frame: Change from baseline CES-D sum score at the end of week 3

    Center for Epidemiologic Studies Depression Scale (CES--D); scale: CES-D sum score; range: 0 - 60; higher scores mean a higher subjective depression level

  3. sleep quality

    Time frame: Change from baseline global PSQI score at the end of week 3

    Pittsburgh Sleep Quality Index (PSQI); scale: global PSQI score; range: 0 - 21; higher scores mean a lower subjective sleep quality

  4. sleep quality - total sleep time

    Time frame: Change of TST at each night during the light intervention period up to 3 weeks

    Wrist actimetry to measure daily total sleep time (TST); scale: sleep duration; range: >0 (minutes); higher TST means longer sleep period

  5. sleep quality - sleep onset latency

    Time frame: change of SOL at each night during the light intervention period up to 3 weeks

    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

  6. sleep quality - wake after sleep onset

    Time frame: change of WASO at each night during the light intervention period up to 3 weeks

    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

  7. sleep quality - sleep efficiency

    Time frame: change of SE at each night during the light intervention period up to 3 weeks

    Wrist actimetry to measure daily sleep efficiency (SE); scale: percentage; range: 0 - 100; higher SE means a higher undisturbed sleep

  8. 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 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

  9. circadian rest/activity rhythm - intradaily variability

    Time frame: change of IS at each of the three light intervention weeks up to 3 weeks

    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

  10. physiological stress reaction

    Time frame: Change from baseline hair cortisol level at the end of week 3

    cortisol level measured from hair sample; scale: real number (pg/mg); range: >0; higher hair cortisol level means higher physiological stress

  11. adverse effects - short-term

    Time frame: day 5

    astenopic complaints measured with 12 items; scale: sum score; range: 10 - 60; higher sum score means more astenopic complaints

  12. adverse effects - long-term

    Time frame: day 15

    astenopic complaints scale measured with 12 items: sum score; range: 10 - 60; higher sum score means more astenopic complaints

Other outcomes

  1. resilience

    Time frame: Change from baseline RS-11 sum score at the end of week 3

    Resilience Scale (RS-11); scale: RS-11 sum score; range: 11 - 77; higher RS-11 sum score means more perceived resilience

  2. stress coping

    Time frame: Change from baseline multidimensional CISS scale at the end of week 3

    Coping Inventory for Stressful Situations (CISS) - 24 items; three-dimensional CISS scale: (a) task-oriented coping; (b) emotion-oriented coping, and (c) avoidance-oriented coping; range for each dimension: 8 - 40; higher score in each dimension means higher preference for particular stress coping style

  3. learning strategies

    Time frame: Change from baseline multidimensional LIST-K scale at the end of week 3

    Learning Strategies of University Students (LIST-K) - 36 items; multidimensional LIST-K scale: 13 subscales; range for each dimension: 3 - 15; higher score in each dimension means higher preference for particular learning strategy

  4. psychological distress

    Time frame: Change from baseline BSI-18 overall score at the end of week 3

    Brief Symptom Inventory (BSI-18); scale: BSI-18 sum score; range: 18 - 90; higher BSI-18 sum score means higher psychological distress

  5. somatic symptoms

    Time frame: Change from baseline SSS-8 sum score at the end of week 3

    The somatic symptom scale (SSS-8); scale: SSS-8 sum score; range: 0 - 32; higher SSS-8 sum score means higher somatic complaints

  6. satisfaction with light intervention - short-term

    Time frame: day 5

    2 items: (a) recommendation of light intervention to a friend and (b) follow-up usage of light intervention for own purposes; scale: binary score ('yes', 'no'); range: 0 - 1; higher binary scores indicate recommendation and follow-up usage of the light intervention

  7. satisfaction with light intervention - long-term

    Time frame: day 15

    2 items: (a) recommendation of light intervention to a friend and (b) follow-up usage of light intervention for own purposes; scale: binary score ('yes', 'no'); range: 0 - 1; higher binary scores indicate recommendation and follow-up usage of the light intervention

  8. daily mood state

    Time frame: changes from before the light intervention of the two-dimensional PANAS scale at the end of light intervention at each weekday during the light intervention period up to 3 weeks

    Positive and Negative Affect Schedule (PANAS); two-dimensional PANAS scale: sum score for positive and negative mood state; range for each dimension: 10 - 50; higher PANAS scores mean higher positive and negative mood state, respectively

  9. weekly social rhythms

    Time frame: changes in SRM scores in week 1, week 2, and week 3

    The Social Rhythm Metric (SRM) measures the regularity in the occurance of 17 daily events; scale: SRM score; range: 0 - 7; higher SRM scores mean more regular occurance of daily events

  10. anxiety state

    Time frame: changes from before the light intervention STAI-state sum score at the end of light intervention in week 1, week 2, and week 3

    State-Trait Anxiety Inventory (STAI - form Y) - 20 state items; scale: STAI-state sum score; range: 20 - 80; higher scores mean a higher subjective current anxiety level

  11. cognitive performance

    Time frame: changes from before the light intervention NLT number of correct answers at the end of light intervention in week 1, week 2, and week 3

    The Number Letter Task (NLT) measures task switching performance; scale: number of correct answers; range: integer greater than or equal to 0; higher NLT scores means a better task switching performance

  12. exam anxiety

    Time frame: changes of multidimensional PAF scale at week 1, week 2, and week 3

    German Test Anxiety Inventory (PAF); four-dimensional PAF scale: (a) excitement, (b) concern, (c) interference, and (d) lack of confidence; range for each dimension: 5 - 20; higher scale means higher test anxiety in the corresponding dimension

Sponsors and collaborators

Lead sponsor

Universitaet Innsbruck

Other

Collaborators

  • Bartenbach GmbH

Registry information

Official study title

Effects of Bright Morning Light Exposure on Students' Stress, Mood, Anxiety, Sleep and, Circadian Rest-activity Cycle

Acronym: BLISS

Important dates

Study start
2020
Primary completion
2024
Study completion
2024
First posted
May 25, 2021
Registry last updated
Jun 26, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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