Effects of Different Colors of Light on Human Physiology

NCT ID: NCT00200863

Last Updated: 2014-08-12

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

NA

Total Enrollment

47 participants

Study Classification

INTERVENTIONAL

Study Start Date

2005-04-30

Study Completion Date

2007-02-28

Brief Summary

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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.

Detailed Description

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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.

Conditions

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Healthy Circadian Rhythm

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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1

420 nm light

Group Type EXPERIMENTAL

Monochromatic visible light exposure

Intervention Type DEVICE

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

2

480 nm

Group Type EXPERIMENTAL

Monochromatic visible light exposure

Intervention Type DEVICE

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

3

507 nm

Group Type EXPERIMENTAL

Monochromatic visible light exposure

Intervention Type DEVICE

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

4

555 nm

Group Type EXPERIMENTAL

Monochromatic visible light exposure

Intervention Type DEVICE

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

5

620 nm

Group Type EXPERIMENTAL

Monochromatic visible light exposure

Intervention Type DEVICE

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

6

460 nm

Group Type EXPERIMENTAL

Monochromatic visible light exposure

Intervention Type DEVICE

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

Interventions

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Monochromatic visible light exposure

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

Intervention Type DEVICE

Eligibility Criteria

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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
Minimum Eligible Age

18 Years

Maximum Eligible Age

30 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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National Center for Complementary and Integrative Health (NCCIH)

NIH

Sponsor Role collaborator

Brigham and Women's Hospital

OTHER

Sponsor Role lead

Responsible Party

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Steven W. Lockley

Neuroscientist

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Steven W Lockley, Ph.D.

Role: PRINCIPAL_INVESTIGATOR

Brigham and Women's Hospital, Harvard Medical School

Locations

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Division of Sleep Medicine, Brigham and Women's Hospital

Boston, Massachusetts, United States

Site Status

Countries

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United States

References

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Gooley JJ, Chamberlain K, Smith KA, Khalsa SB, Rajaratnam SM, Van Reen E, Zeitzer JM, Czeisler CA, Lockley SW. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. J Clin Endocrinol Metab. 2011 Mar;96(3):E463-72. doi: 10.1210/jc.2010-2098. Epub 2010 Dec 30.

Reference Type DERIVED
PMID: 21193540 (View on PubMed)

Other Identifiers

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R01AT002129-01

Identifier Type: NIH

Identifier Source: secondary_id

View Link

R01AT002129-01

Identifier Type: NIH

Identifier Source: org_study_id

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