Light

Light shapes hormone balance through the eyes and skin, not only vision. Mainstream textbooks long claimed visible light was not chemically active in animal tissues. Peat cited Otto Warburg and later enzyme studies showing visible light restores respiratory pigment activity, and that blue light inhibits while red light activates respiratory enzymes.

Penetrating red light is possibly the fundamental anti-stress factor for all organisms. The chronic deficiency of such light is, I think, the best explanation for the deterioration which occurs with aging.

— Ray Peat

When I moved from Mexico, first to Montana and then to Oregon in 1966, I became very conscious of how light affects the hormones and the health. (For example, in Montana I experienced an interesting springtime shedding of body hair.) Many people who came to cloudy Eugene to study, and who often lived in cheap basement apartments, would develop chronic health problems within a few months. Women who had been healthy when they arrived would often develop premenstrual syndrome or arthritis or colitis during their first winter in Eugene.

— Ray Peat

Peat described "winter sickness" in cloudy climates: absence of bright light can leave Estrogen and Prolactin unopposed by Progesterone, worsening PMS, arthritis, colitis, and fertility problems seasonally. Bright artificial light can regulate hormones; he noted Times Square sparrows mating in winter under city lights.

Darkness and stress hormones (melatonin, prolactin, TSH) increase retinal sensitivity to injury from light that would otherwise be harmless. Cytochrome oxidase is damaged by stress and blue light and restored by red light, Thyroid, and Progesterone.

Practical themes: daylight exposure, Red light and incandescent or halogen sources over blue-heavy LEDs at night, orange lenses to block blue when needed. See Roadmap/08 - Buy list & Life quality improvers, Harm reduction.

Light therapy

Controlled bright light exposure shifts circadian timing and mood; mainstream psychiatry uses it for seasonal affective disorder and some sleep disorders. In a 22-day randomized trial of 22 patients with seasonal depression, daily light treatment cut depression scores by 65.2% with standard 10,000 lux white light and by 76.4% with low-intensity 750 lux blue-enriched light, with no significant difference between the two intensities.

The absence of bright light would create a progesterone deficiency, and would leave estrogen and prolactin unopposed.

— Ray Peat

If the sparrows of Times Square mated in the winter because of the bright lights, it seemed clear that bright artificial light would be helpful in regulating human hormones.

— Ray Peat

Daytime bright light supports Thyroid and opposes darkness-driven prolactin and TSH. See Sleep, Harm reduction.

Incandescent and other light sources

Fluorescent-light exposure induced highly conserved inflammatory and acute-phase-response gene programs across zebrafish, medaka, and hairless mice in skin, brain, and liver — pathways driven mainly by TNF and IL1B signaling and interpreted by the authors as an ancient vertebrate stress response to artificial light. Incandescent lamps heat a tungsten filament until it glows, producing a continuous spectrum rich in red and near-infrared wavelengths; halogen bulbs are a related design. White LEDs often peak in blue, unlike incandescent warmth.

By the 1960s, several studies had been published showing the inhibition of respiratory enzymes by blue light, and their activation by red light.

— Ray Peat

Red light is protective, blue light (or u.v.) is harmful, so wearing orange lenses would be helpful.

— Ray Peat

Blue light inhibited cytochrome oxidase and caused retinal injury in rat experiments. Daylight, incandescent or halogen indoor lighting, and orange lenses are favored over blue-heavy LEDs at night. See Red light for red/NIR light therapy devices and protocols.

Quotes

Sunshine is free nutrition that must be utilized at every given opportunity. Every day the sun shines you must consume its light. Better than the most expensive D3 supplement, UV lamp, and infrared panel.

— Ray Peat