Acute Effects of Whole Body Blue Light Exposure on Blood Pressure

Study Overview
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Brief Summary
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Ultraviolet light exposure was shown to be able to release nitric oxide from the skin into the blood stream and lead to an acute decrease in blood pressure and increase in vascular function. Additionally, preliminary work indicates that UV free blue light also releases nitric oxide in the skin mediating similar effects as seen with ultraviolet light A(UVA). It is the goal of the present experimental study to investigate the hemodynamic effects of whole body blue light exposure including blood pressure, endothelial function and vascular stiffness. Therefore, healthy volunteers will be exposed to 30 minutes whole body blue light (453 nm wavelength) and the change in blood pressure and endothelial function (Flow mediated dilation (FMD)), heart rate, forearm-blood flow, forearm vascular resistance central blood pressure and vascular stiffness ( pulse wave analysis by sphygmocor) will be measured. In this randomized controlled cross-over study, 20 healthy subjects aged 30 to 60 years will participate.

Official Title
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Acute Effects of Whole Body Blue Light Exposure on Blood Pressure, Endothelial Function and Vascular Stiffness

Conditions
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Blue Light

Intervention / Treatment
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* Procedure: Blue light
* Procedure: control exposure


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: healthy, male subjects age between 30 and 60 years signed patient informed consent Exclusion Criteria: diabetes mellitus acute inflammation (CRP >0.5mg/dl) cardiac arrythmia active cancer renal failure heart failure (NYHA II-IV) arterial hypotension (systolic pressure <100 mmHg) treatment with antihypertensive drugs dermatosis of the eyelid porphyria or hypersensitivity to porphyrins congenital or aсquired immune deficiency genetic conditions that cause an increased sensitivity to light or an increased risk to dermatological cancer (such as xeroderma pigmentosum, cockayne syndrome, bloom syndrome) previous intake or use of photosensitizing drugs, food or cosmetics (e.g. psychiatric medication, antibiotics, cardiovascular drugs, hormone, Hypericum, Bergamot orange) or use of perfumes

Ages Eligible for Study
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Minimum Age: 30 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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Male

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: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Blue light<br>Each subject will be undergo a whole body exposure to blue light (453 nm wavelength) for 30 minutes. | Procedure: Blue light<br>* Subjects will be exposed to blue light (453 nm wavelength) for 30 minutes<br>|
| Placebo Comparator: Control exposure<br>Each participant will also undergo a control examination, where the body will be covered with a light tight foil during blue light exposure for 30 minutes. | Procedure: control exposure<br>* Subjects will get control exposure to 30 minutes of whole body, which causes only comparable warming of skin as with blue light exposure.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change of peripheral blood pressure | Change of peripheral blood pressure as measured before, during and up to 2 hours after 30 min blue light as compared to control | baseline, during 30 min exposure and 2 hours thereafter | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in endothelial function | measured by flow mediated dilation (FMD) before, immediately after 30 min exposure and at 2 h thereafter | baseline, during 30 min exposure and 2 hours thereafter | 
| Change from baseline heart rate | measured by electrocardiography (ECG) before, during and up to 2 hours after 30 min blue light as compared to control | baseline, during 30 min exposure and 2 hours thereafter | 
| Change from baseline forearm blood flow | measured by ultrasound before, immediately after 30 min exposure and at 2 h thereafter | baseline, during 30 min exposure and 2 hours thereafter | 
| Change from baseline forearm vascular resistance | measured by ultrasound before, immediately after 30 min exposure and at 2 h thereafter | baseline, during 30 min exposure and 2 hours thereafter | 
| Change from baseline central blood pressure | measured by applanation tonometry before, immediately after 30 min exposure and at 2 h thereafter | baseline, during 30 min exposure and 2 hours thereafter | 
| Change from baseline vascular stiffness | measured by applanation tonometry before, immediately after 30 min exposure and at 2 h thereafter | baseline, during 30 min exposure and 2 hours thereafter | 
| Change from baseline NO-species | determined by chemiluminescence before, immediately after 30 min exposure and at 2 h thereafter | baseline, during 30 min exposure and 2 hours thereafter | 
| Change from baseline Cortisol | measured before, immediately after 30 min exposure and at 2 h thereafter | baseline, during 30 min exposure and 2 hours thereafter | 
| Change from baseline Endorphins | measured before, immediately after 30 min exposure and at 2 h thereafter | baseline, during 30 min exposure and 2 hours thereafter | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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blue light, blood pressure, vascular function, endothelial function, health volunteers