Light
127 sourcesRay Peat considered light exposure an important factor in metabolic health, drawing on extensive research showing that red and near-infrared light support mitochondrial function, while blue light and darkness promote stress responses. He noted that seasonal depression, insomnia, and metabolic slowdowns in winter are partly driven by reduced light exposure and the hormonal shifts (increased melatonin, prolactin, and cortisol) associated with long dark periods.
Peat recommended bright light exposure during the day, incandescent lighting rather than fluorescent or LED (which have excessive blue spectrum), and noted that red light therapy has measurable effects on cellular respiration by stimulating cytochrome c oxidase in the electron transport chain.
Key Positions
- Red and near-infrared light directly stimulate cytochrome c oxidase in mitochondria
- Incandescent bulbs provide a warm spectrum supporting metabolic function; LEDs and fluorescents have excess blue
- Darkness increases melatonin, prolactin, and cortisol — all stress mediators
- Bright light exposure suppresses prolactin and supports thyroid function
- Seasonal light deprivation contributes to winter depression, weight gain, and immune suppression
- UV light has both beneficial effects (vitamin D) and damaging effects — PUFAs increase UV sensitivity
- Sunlight exposure is important but risk is modified by dietary PUFA intake