Overview
Blue light is next to ultraviolet light for toxicity. Biologists have known that pure blue light knocks out plant mitochondria for over 50 years. What saves sunlight from being a straight poison is that it also contains red light, which neutralises the damage. The problem with modern indoor life is that LED bulbs, fluorescent tubes, computer screens and phones push out the blue end of the spectrum without the balancing red. Blue light pushes electrons into an excited, unstable state by inhibiting cytochrome c oxidase, the last enzyme needed before food meets oxygen to make ATP (energy).
Key Points
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Blue light damages mitochondria in a way comparable to x-rays or ultraviolet when the balancing red light is removed. If you put a plant that thrives in sunlight into pure blue light, the mitochondria are damaged almost as if the plant were being irradiated with x-rays or ultraviolet. Add back the rest of the spectrum and something about the red light neutralises the toxic effect. This has been shown in plant physiology experiments going back fifty or sixty years.
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Blue light produces a degree of ionisation, even though it is classified as non-ionising. When you go from full-spectrum light centred on yellow to pure blue, the excitation of electrons reaches the level where it damages mitochondrial energy production. Ultraviolet and blue light cause chemical effects very similar to x-rays; the difference is only that ultraviolet and blue are absorbed in the first few millimetres of skin, while x-rays pass deeper. Blue light can also damage DNA directly, despite the official story that only ionising radiation does that.
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Red light detoxifies blue light, ultraviolet, and even gamma radiation by restoring electrons to their resting state. In a Russian experiment, frogs given a lethal dose of gamma rays did not get sick at all if bright red light was shone on them within the first hour. The same quenching effect can be seen in seeds, hair, and plant tissue.
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Blue light damages the retina through electron excitation, and red light applied quickly can reverse it. If someone burns their retina with ultraviolet, red light applied soon enough prevents the burning. The same electron-trap mechanism that turns desert glass purple is what injures the eye, and red light at the right energy lifts the electrons out of the trap and restores them to their normal position. The amount of exposure matters: looking directly at a phone screen for hours is a real concern, but a glance before bed is not.
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Cytochrome oxidase, the respiratory enzyme at the end of the mitochondrial energy chain, is degraded by darkness and restored by red light. The enzyme contains copper in the blue oxidation state, and blue copper absorbs red light. After eight to fifteen hours of darkness the copper detaches and the enzyme loses activity. Red light passes freely through tissue without being absorbed randomly, reaches the copper in the enzyme, and restores it. This is why mortality climbs at the end of winter and why we should not be in total darkness for longer than it takes to sleep.
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Fluorescent lights, including the compact squiggly ones, are worse than most people realise because they emit in radio frequency and microwave frequencies on top of the blue-biased visible spectrum. They also lack the red light that incandescent bulbs produce. The compact fluorescents were promoted as energy saving, but they cause cancer-promoting effects in tissue and their disposal is energy-expensive because of the mercury. Incandescent bulbs are still the best answer, with LEDs a distant second.
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Incandescent bulbs produce more red than blue because the filament runs cooler than the sun. If you look at an incandescent bulb through a prism, the red end is substantially more intense than the blue and green. A 130-volt clear-front bulb run on a standard 120-volt circuit puts out even less blue and more red than a standard incandescent, and 250-watt versions cost around four dollars. A 250-watt reflector bulb called an infrared bulb looks like ordinary white light but runs at a lower temperature and is heavier on the red.
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Red light penetrates tissue deeply enough to reach bone marrow. Using a paddle of about 100 red LEDs pressed under the thigh in a dark room, the silhouette of the femur was visible straight through, meaning the light was passing entirely through muscle and bone. Semi-opaque tissues are essentially transparent to red because blue and green are being absorbed, but red is not. This is why red light therapy works systemically even when only part of the body is exposed.
Notable Quotes
"If you use a blue light rather than a full spectrum centered on yellow, the excitation of the electrons is enough to damage the mitochondrial energy production."
[Ray Peat — KMUD: Radiation]
"Blue light, for example, does damage DNA."
[Ray Peat — Bioenergetic Nutrition Basics, The Ray Peat Diet, Appetite and Metabolism]
"Those little fluorescent things are going to cause an epidemic of cancer."
[Ray Peat — KMUD: Cancer Treatment]
"Blue light actually accelerates the activity of the enzyme synthesizing serotonin"
[Georgi Dinkov — Anxiety, Sleep, GABA, Serotonin & Why we Don't Want too much Serotonin - Georgi Dinkov]
Important Things To Consider
LED and fluorescent nightlights are worse than darkness for children. Blue-light nightlights are linked to myopia in children, and blue light after dark stimulates cravings and cortisol. If a nightlight is needed, an amber or red one is the only sensible choice.
The amount of blue from a phone or tablet is small enough that casual use will not burn the retina, but hours of direct staring at night is a real concern. A glance at a phone in bed is not a serious amount, but holding a bright screen close to the face for long periods is closer to the hazardous end of the spectrum.
A tanning bed is pure ultraviolet with no protective red light and will slightly suppress the immune system. Your white blood cells circulate through the skin and get a small sunburn each session. Until you are tanned enough that the UV does not reach them, real sunlight is the better way to raise vitamin D because sunlight includes the red light that cancels the damage.
Blue light after sunset raises cortisol and lowers melatonin. The stress system recognises darkness within 15 minutes and starts raising cortisol. Blue light telling the brain it is noon at 11 pm produces the same cortisol rise as a real stressor, with the added problem that the person is awake and exposed to screens rather than asleep in the dark.
Blue-blocking glasses are a partial mitigation, not a substitute for sunlight. Amber or red-tinted blue-blocking glasses in the evening reduce the suppressive effect of screens and indoor lighting on melatonin. But they do not replace the benefit of actual sunlight during the day, which provides the red and near-infrared that activate cytochrome c oxidase.
Mitochondria evolved from primitive organisms, which is likely why blue light damages them. Blue and UV light are used to kill bacteria, fungi, and viruses because these primitive organisms cannot survive the metabolic inhibition. Mitochondria are thought to have evolved from a symbiotic relationship with a similar primitive cell, which is why the same wavelengths that sterilize countertops also damage the mitochondria in our own cells.