Effects of Different Colors of Light on Human Physiology
Status
Conditions
Treatments
Study type
Funder types
Identifiers
Details and patient eligibility
About
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.
Full 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.
Enrollment
Sex
Ages
Volunteers
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
Trial design
Primary purpose
Allocation
Interventional model
Masking
47 participants in 6 patient groups
Trial contacts and locations
Loading...
Data sourced from clinicaltrials.gov
Clinical trials
Research sites
Resources
Legal