Crystals and Gemstones (Test blog)
How Light Shapes Our Biology: The Science of Colour Therapy
- The biological foundation: humans are light-regulated organisms
- About 1–2% of all human genes are under circadian control — meaning their expression changes depending on light exposure.
- Light not only enables vision but also regulates sleep, mood, energy metabolism, immune function, and hormones.
- These effects are mediated by non-visual photoreceptors in the eye, especially intrinsically photosensitive retinal ganglion cells (ipRGCs) that contain the pigment melanopsin.
How Light Shapes Our Biology: The Science of Colour Therapy
- The biological foundation: humans are light-regulated organisms
- About 1–2% of all human genes are under circadian control — meaning their expression changes depending on light exposure.
- Light not only enables vision but also regulates sleep, mood, energy metabolism, immune function, and hormones.
- These effects are mediated by non-visual photoreceptors in the eye, especially intrinsically photosensitive retinal ganglion cells (ipRGCs) that contain the pigment melanopsin.
- Neural and endocrine pathways
Retina → Hypothalamus → Pineal gland
Light → ipRGCs → SCN (circadian clock) → Pineal gland.
In darkness, the pineal gland converts serotonin into melatonin.
In light (especially blue), melatonin synthesis is suppressed, leading to wakefulness.
Hypothalamic–pituitary axis modulation
Light intensity and spectrum affect the release of CRH (corticotropin-releasing hormone) and ACTH, influencing cortisol levels.
Morning blue light → ↑ cortisol → alertness, energy.
Evening exposure → cortisol remains high → insomnia and stress.
Serotonin and dopamine
Bright light boosts tryptophan hydroxylase, the enzyme for serotonin synthesis.
Serotonin is a precursor for melatonin, so daytime exposure builds the chemical foundation for nighttime sleep.
Dopaminergic pathways in the retina and limbic system are also light-sensitive, influencing motivation and pleasure.
- Psychological and perceptual dimensions
Light intensity and spectrum affect the release of CRH (corticotropin-releasing hormone) and ACTH, influencing cortisol levels.
Morning blue light → ↑ cortisol → alertness, energy.
Evening exposure → cortisol remains high → insomnia and stress.