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Effects of Different Colors of Light on Human Physiology

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT00200863
First Posted: September 20, 2005
Last Update Posted: August 12, 2014
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Collaborator:
National Center for Complementary and Integrative Health (NCCIH)
Information provided by (Responsible Party):
Steven W. Lockley, Brigham and Women's Hospital
  Purpose
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.

Condition Intervention
Healthy Circadian Rhythm Device: Monochromatic visible light exposure

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Mechanism Underlying the Effects of Blue Light in Humans

Further study details as provided by Steven W. Lockley, Brigham and Women's Hospital:

Primary Outcome Measures:
  • Subjective alertness prior to, during and after light exposure [ Time Frame: 9.5 hours ]
  • Auditory psychomotor performance prior to, during and after light exposure [ Time Frame: 9.5 hours ]
  • EEG power frequency prior to, during and after light exposure [ Time Frame: 9.5 hours ]
  • Plasma melatonin and cortisol prior to, during and after light exposure [ Time Frame: 60 hours ]
  • Heart rate, blood pressure, respiration rate and temperature prior to, during and after light exposure [ Time Frame: 9.5 hours ]
  • Urinary catecholamines prior to, during and after light exposure [ Time Frame: 32 hours ]

Enrollment: 47
Study Start Date: April 2005
Study Completion Date: February 2007
Primary Completion Date: February 2007 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: 1
420 nm light
Device: Monochromatic visible light exposure
Monochromatic light in the visible range from 420-620 nm up to 60uW/cm2 for 6.5 hours
Experimental: 2
480 nm
Device: Monochromatic visible light exposure
Monochromatic light in the visible range from 420-620 nm up to 60uW/cm2 for 6.5 hours
Experimental: 3
507 nm
Device: Monochromatic visible light exposure
Monochromatic light in the visible range from 420-620 nm up to 60uW/cm2 for 6.5 hours
Experimental: 4
555 nm
Device: Monochromatic visible light exposure
Monochromatic light in the visible range from 420-620 nm up to 60uW/cm2 for 6.5 hours
Experimental: 5
620 nm
Device: Monochromatic visible light exposure
Monochromatic light in the visible range from 420-620 nm up to 60uW/cm2 for 6.5 hours
Experimental: 6
460 nm
Device: Monochromatic visible light exposure
Monochromatic light in the visible range from 420-620 nm up to 60uW/cm2 for 6.5 hours

Detailed 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.

  Eligibility

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 30 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

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
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00200863


Locations
United States, Massachusetts
Division of Sleep Medicine, Brigham and Women's Hospital
Boston, Massachusetts, United States, 02115
Sponsors and Collaborators
Brigham and Women's Hospital
National Center for Complementary and Integrative Health (NCCIH)
Investigators
Principal Investigator: Steven W Lockley, Ph.D. Brigham and Women's Hospital, Harvard Medical School
  More Information

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Steven W. Lockley, Neuroscientist, Brigham and Women's Hospital
ClinicalTrials.gov Identifier: NCT00200863     History of Changes
Other Study ID Numbers: R01AT002129-01 ( U.S. NIH Grant/Contract )
First Submitted: September 12, 2005
First Posted: September 20, 2005
Last Update Posted: August 12, 2014
Last Verified: August 2014

Keywords provided by Steven W. Lockley, Brigham and Women's Hospital:
light
wavelength
action spectrum
circadian
melatonin
alertness
performance
arousal