Systematically Assessing Effects of Colored Light on Humans With a Multi-modal Approach (Substudy 1 of 7)

Study Overview
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Brief Summary
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NOTE: This is the first 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 5 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 Red 30 lux<br>The participants will be exposed to red LED light at a illuminance of 30 lux at eye level for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. | 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 Red 120 lux<br>The participants will be exposed to red LED light at a illuminance of 120 lux at eye level for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. | 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 Blue 30 lux<br>The participants will be exposed to blue LED light at a illuminance of 30 lux at eye level for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. | 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 Blue 120 lux<br>The participants will be exposed to blue LED light at a illuminance of 120 lux at eye level for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. | 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>|
| No Intervention: darkness<br>The participants will not be exposed to any light but stay in darkness for 15 minutes. The colored light exposure will be preceded by sitting 8 minutes in darkness and followed by sitting 20 minutes in darkness. | |

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 concentration during colored light exposure compared with a baseline and a recovery period | 3 hemoglobin concentrations will be analyzed: of oxygenated hemoglobin, of deoxygenated hemoglobin, and of total hemoglobin. | 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 | Heart rate variability variables are: the standard deviation of the NN Intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD), the power of the high-frequency component (HF, 0.15-0.4 Hz), the power of the low-frequency component (LF, 0.04-0.15 Hz), the power of the very low-frequency component (VLF, <0.04 Hz), normalized LF and HF components, and the LF/HF ratio. | 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 | The tonic and phasic parts of the electro-dermal activity will be analyzed. | 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 | The systolic, diastolic, and mean arterial pressure will be analyzed. | 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 | The partial pressure of carbon dioxide will be assessed by the end-tidal partial pressure of carbon dioxide of the exhalation air. | 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) | 

 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