Effects of Different Colors of Light on Human Physiology

Healthy Clinical Trial

Official title:

Mechanism Underlying the Effects of Blue Light in Humans

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00200863
• Other study ID #: R01AT002129-01
• Secondary ID: R01AT002129-01
• Status: Completed
• Phase: N/A
• First received: September 12, 2005
• Last updated: August 8, 2014
• Start date: April 2005
• Est. completion date: February 2007

Study information

• Verified date: August 2014
• Source: Brigham and Women's Hospital
• Contact: n/a
• Is FDA regulated: No
• Health authority: United States: Federal Government
• Study type: Interventional

Clinical Trial Summary

This study will determine which color of light is most effective in stimulating a range of biological functions in humans including activation of sleep-wake regulatory system (alertness, performance, microsleeps, brain activity), activation of the nervous system (heart rate, temperature, blood pressure, breathing rate), and shifting the timing of the internal 24-hour (circadian) pacemaker.

Description:

Light has long been proposed to have a stimulatory effect on a range of biological functions in humans including increased feelings of activation, such as improved alertness or ability to perform. The mechanisms underlying how light stimulates these neurobiological systems remain to be elucidated. We propose to investigate the effects of different colors of light on human physiology, and in particular, test the claims that specific colors of light preferentially stimulate neurobiological, physiological and hormonal systems. Using classical photobiological techniques, we will construct action spectra for the effects of different colors of light on a range of non-image forming responses in humans.

We will test the hypotheses that: 1) light-induced activation of the neurobiological sleep-wake regulatory system, as indicated by increased alertness, faster reaction time, suppression of EEG alpha activity, microsleeps and slow rolling eye movements, and suppression of pineal melatonin, is most sensitive to retinal exposure to short wavelength blue light (460 nm) compared to equal photons of other colors of visible light; 2) light-induced activation of autonomic and hypothalamic-pituitary-adrenal axis measures of arousal, as indicated by increased heart rate variability, core body temperature, blood pressure, respiration rate, plasma cortisol levels and urinary catecholamines, is most sensitive to exposure to short wavelength blue light (460 nm) compared to equal photons of other colors; 3) phase shifts of the human circadian pacemaker, as assessed by changes in temperature, melatonin and cortisol rhythms, are most sensitive to exposure to short wavelength blue light (460 nm) compared to equal photons of other colors. The resultant action spectra will help to identify the photoreceptor mechanism(s) by which light activates arousal and circadian resetting, these non-image-forming physiological responses and enable us to distinguish between major candidate photoreceptive mechanisms, including potential novel photoreceptor systems, that might mediate such responses.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 47
• Est. completion date: February 2007
• Est. primary completion date: February 2007
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 18 Years to 30 Years

Eligibility

Inclusion Criteria:

• Free from any acute, chronic or debilitating medical, psychological, or ophthalmological conditions

• Drug-free (including caffeine, nicotine, and alcohol) for entire study duration

Exclusion Criteria:

• History of drug or alcohol dependency

• History of psychiatric illnesses or evidence of psychopathology according to standardized questionnaires, or in a structured clinical interview

• Night shift work during the past 3 years

• Transmeridian travel in the last 3 months

Study Design

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment

Related Conditions & MeSH terms

• Circadian Rhythm
• Healthy

Intervention

Device:
• Monochromatic visible light exposure
Monochromatic light in the visible range from 420-620 nm up to 60uW/cm2 for 6.5 hours

Locations

Country	Name	City	State
United States	Division of Sleep Medicine, Brigham and Women's Hospital	Boston	Massachusetts

Sponsors (2)

Lead Sponsor	Collaborator
Brigham and Women's Hospital	National Center for Complementary and Integrative Health (NCCIH)

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Subjective alertness prior to, during and after light exposure		9.5 hours	No
Primary	Auditory psychomotor performance prior to, during and after light exposure		9.5 hours	No
Primary	EEG power frequency prior to, during and after light exposure		9.5 hours	No
Primary	Plasma melatonin and cortisol prior to, during and after light exposure		60 hours	No
Primary	Heart rate, blood pressure, respiration rate and temperature prior to, during and after light exposure		9.5 hours	No
Primary	Urinary catecholamines prior to, during and after light exposure		32 hours	No