Systematically Assessing Effects of Colored Light on Humans With a Multi-modal Approach (Substudy 4 of 7)

Study Overview
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Brief Summary
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NOTE: This is the fourth of in total 7 sub-studies related to the Ethics Committee of the Canton of Bern Ref. No. KEK-BE 2016-00674. This sub-study includes 50 participants and 8 arms, in total 350 participants will be assessed in all 7 sub-studies. General study information: This is a randomized, cross-over, quantitative study, which investigates physiological variables, mood, and affect of healthy participants in response to colored light exposure. The Participants take part in 5-8 arms and are exposed to colored light only, or are additionally asked to solve cognitive tasks during the colored light exposure. Primary aim is to measure the change in several physiological variables, mood, and affect during colored light exposure of 15 or 45 minutes. The risk for the participants is negligible and comparable to the risk during daily life.

Official Title
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Systematically Assessing Effects of Colored Light on Humans With a Multi-modal Approach

Conditions
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Exposure to Man-made Visible Light

Intervention / Treatment
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* Other: Visible light exposure


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Normal color vision Right handed Written informed consent Exclusion Criteria: Smoking Any kind of diagnosed sleep disorder or neurological or psychiatric disorder in the last 3 months Acute severe traumas Chronic diseases with the necessity for medication Use of recreational drugs Regular intake of medication that would affect the outcome measures Regular excessive alcohol use (> 18 standard units / week) Transmeridian travel in the last month (crossed > 1 time zone border) Night shift word during the last month

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Visible light exposure cognitive Red<br>The participants will be tested for cognitive performance (verbal fluency task, arithmetic task, word repetition task) during exposure to red LED light at a fixed illuminance for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. The participants will additionally perform hyperventilation and hypoventilation tasks. | Other: Visible light exposure<br>* Subjects will be exposed to visible colored light for 15 minutes. The visible light will be generated by red-green-blue light emitting diodes light cans.<br>|
| Experimental: Visible light exposure cognitive Orange<br>The participants will be tested for cognitive performance (verbal fluency task, arithmetic task, word repetition task) during exposure to orange LED light at a fixed illuminance for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. The participants will additionally perform hyperventilation and hypoventilation tasks. | Other: Visible light exposure<br>* Subjects will be exposed to visible colored light for 15 minutes. The visible light will be generated by red-green-blue light emitting diodes light cans.<br>|
| Experimental: Visible light exposure cognitive Yellow<br>The participants will be tested for cognitive performance (verbal fluency task, arithmetic task, word repetition task) during exposure to yellow LED light at a fixed illuminance for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. The participants will additionally perform hyperventilation and hypoventilation tasks. | Other: Visible light exposure<br>* Subjects will be exposed to visible colored light for 15 minutes. The visible light will be generated by red-green-blue light emitting diodes light cans.<br>|
| Experimental: Visible light exposure cognitive Green<br>The participants will be tested for cognitive performance (verbal fluency task, arithmetic task, word repetition task) during exposure to green LED light at a fixed illuminance for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. The participants will additionally perform hyperventilation and hypoventilation tasks. | Other: Visible light exposure<br>* Subjects will be exposed to visible colored light for 15 minutes. The visible light will be generated by red-green-blue light emitting diodes light cans.<br>|
| Experimental: Visible light exposure cognitive Cyan<br>The participants will be tested for cognitive performance (verbal fluency task, arithmetic task, word repetition task) during exposure to cyan LED light at a fixed illuminance for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. The participants will additionally perform hyperventilation and hypoventilation tasks. | Other: Visible light exposure<br>* Subjects will be exposed to visible colored light for 15 minutes. The visible light will be generated by red-green-blue light emitting diodes light cans.<br>|
| Experimental: Visible light exposure cognitive Blue<br>The participants will be tested for cognitive performance (verbal fluency task, arithmetic task, word repetition task) during exposure to blue LED light at a fixed illuminance for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. The participants will additionally perform hyperventilation and hypoventilation tasks. | Other: Visible light exposure<br>* Subjects will be exposed to visible colored light for 15 minutes. The visible light will be generated by red-green-blue light emitting diodes light cans.<br>|
| Experimental: Visible light exposure cognitive Violet<br>The participants will be tested for cognitive performance (verbal fluency task, arithmetic task, word repetition task) during exposure to violet LED light at a fixed illuminance for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. The participants will additionally perform hyperventilation and hypoventilation tasks. | Other: Visible light exposure<br>* Subjects will be exposed to visible colored light for 15 minutes. The visible light will be generated by red-green-blue light emitting diodes light cans.<br>|
| Experimental: Visible light exposure cognitive White<br>The participants will be tested for cognitive performance (verbal fluency task, arithmetic task, word repetition task) during exposure to white LED light at a fixed illuminance for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. The participants will additionally perform hyperventilation and hypoventilation tasks. | Other: Visible light exposure<br>* Subjects will be exposed to visible colored light for 15 minutes. The visible light will be generated by red-green-blue light emitting diodes light cans.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in cerebral tissue oxygen saturation during colored light exposure compared with a baseline and a recovery period |  | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 
| Change in cerebral hemoglobin concentrations during colored light exposure compared with a baseline and a recovery period |  | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 
| Change in variables of the heart rate variability during colored light exposure compared with a baseline and a recovery period |  | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 
| Change in variables of the electro-dermal activity during colored light exposure compared with a baseline and a recovery period |  | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 
| Change of the blood pressure during colored light exposure compared with a baseline and a recovery period |  | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 
| Change of the partial pressure of carbon dioxide during colored light exposure compared with a baseline and a recovery period |  | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 
| Change of the respiration rate during colored light exposure compared with a baseline and a recovery period |  | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 
| Change of the heart rate during colored light exposure compared with a baseline and a recovery period |  | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 
| Change of the pulse-respiratory quotient during colored light exposure compared with a baseline and a recovery period | The pulse-respiratory quotient will be calculated as heart rate divided by the respiration rate. | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 
| Change of the arterial oxygen saturation during colored light exposure compared with a baseline and a recovery period |  | 43 minutes (8 min baseline, 15 min colored light exposure, 20 min recovery) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in verbal fluency task performance during exposure to different colors. | A word repetition task will serve as control condition. | 1-4 weeks | 
| Change in arithmetic task performance during exposure to different colors. | A word repetition task will serve as control condition. | 1-4 weeks | 
| Difference in brain activity evoked from the verbal fluency task for the different colored light conditions. | A word repetition task will serve as control condition. | 1-4 weeks | 
| Difference in brain activity evoked from the arithmetic task for the different colored light conditions. | A word repetition task will serve as control condition. | 1-4 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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cerebral oxygen metabolism, functional near-infrared spectroscopy, partial pressure of carbon dioxide, heart rate variability, blood pressure, affect, mood, respiration, systematic randomized cross-over study, systemic physiology, electro-dermal activity, pulse-respiratory quotient