Mitochondriak® Red Bulbs and Blue Light Blocking Glasses: A Real Spectrometer Test

How much blue light does a red light bulb really give off, and what do blue light blocking glasses let through when you check them with an instrument instead of your eyes? We tested our lights with two certified spectrometers in a dark room: Mitochondriak® red bulbs emit practically 0% of their energy below 500 nm, our glasses blocked 100% of blue and green light up to 550 nm, and a classic incandescent bulb showed a continuous spectrum that runs deep into the infrared. Why does a filament bulb shine like a small sun, and why does lux not tell you the whole story? Instead of guessing, we have numbers.

Results at a glance

In short: our red lights shine where your body clock barely listens. Their peaks sit in the red, between 631 and 656 nm, we measured practically zero blue, and at the same brightness they send your body a daytime signal 71 to 270 times weaker than an ordinary white LED. They do not flicker. And the glasses strip 99.7% of that signal from a white LED, leaving nothing but clean red light.

How did we test our lights and glasses?

Simply, and the same way every time, so the test is transparent and precise. Each light shone in a dark room with two instruments in front of it. The main certified spectrometer, the OHSP-350UVF, records the spectrum from 230 to 900 nm in 1 nm steps. The second, a calibrated UPRtek CV600 with its calibration certificate, covers 380 to 780 nm. It served as an independent second check, and it is also an excellent, precise flicker meter. When two independent instruments show the same spectral shape and the same peak, it is no coincidence. Period.

Mitochondriak Lab is our measuring bench: the place where we do not estimate Mitochondriak® lights or copy numbers from a catalog, we measure them. All measurements were taken on 21 October 2026.

• Distance: the E27 and E14 bulbs and the incandescent bulb at 50 cm, the GU10 spotlight at 30 cm on the beam axis, the red night light up close at 10 to 15 cm.
• Reference: an ordinary white LED bulb (3,700 K) and the midday sun on the same day.
• Glasses: the same white LED, measured once without the glasses and once through the lenses held right in front of the sensor.
• Calculations: from the spectra we calculated melanopic EDI and the share of light below 500 and 550 nm according to the CIE S 026 standard [R].

Why isn't lux enough, and what is melanopic EDI?

Lux tells you how brightly you see, not what time of day the light announces to your body. Describing light with a single lux number is like describing an avocado by a sliver of its pit. Your eye is not a hardware-store light meter. Besides rods and cones, it holds cells with the pigment melanopsin, which do not form images. They tell time. They are most sensitive to blue light around 480 nm.

Melanopic EDI stands for melanopic equivalent daylight illuminance. In plain words, it tells you how much “daytime” signal a light sends to your body clock, expressed in lux of daylight. Technically, it is the illuminance of standard daylight D65 that would stimulate melanopsin exactly as much as the light being measured. It is calculated from the spectrum according to CIE S 026, the standard of the International Commission on Illumination [R].

An international group of 18 sleep and circadian experts turned it into simple recommendations: during the day at least 250 lx melanopic EDI at eye level, in the evening, starting at least three hours before bedtime, no more than 10 lx, and in the bedroom during sleep no more than 1 lx [R]. This is an expert consensus built on studies in humans.

The chart says it all. Every 100 lux from an ordinary white LED sends your body the signal of 61 lux of daylight. With our red lights it is 0.2 to 0.9 lx. The E27 red bulb has a melanopic EDI of 0.2 lx at 50 cm, fifty times below the evening ceiling of 10 lx. To cross it, you would need thousands of lux of red light. Does that make sense?

How many lumens does a red light bulb have, and why is that number misleading?

Lumens and lux both weight light by the eye's sensitivity curve, which peaks in the green at 555 nm and drops quickly in deep red. On paper, a red bulb therefore looks “weaker,” even though it emits a similar amount of power to other bulbs. Our E27 and E14 red bulbs give roughly 250 to 350 lumens, and the GU10 spotlight about 140 lumens. In the evening, though, a different number decides: how much daytime signal the light sends to your clock. With red, that is almost zero.

Do red light bulbs emit blue light? E27, E14 and GU10 tested

Practically none. Mitochondriak® E27, E14 and GU10 red bulbs are light bulbs without blue light: what the spectrometer picks up below 500 nm is just the instrument's background noise. At the same brightness, they send your body clock a signal 71 to 270 times weaker than an ordinary white LED. All three shine where melanopsin is nearly blind. Yet they are not identical. Each has its own shade of red.

“Practically 0%” means that the value measured below 500 nm (0.0 to 0.06%) sits at the level of the spectrometer's background noise, not light from the bulb. FWHM spectral width shows how wide the band is at half the height of the peak.

The E27 is the deepest red of our bulbs. Its wavelength peaks at 656 nm, and with 95% of its energy above 620 nm it sits farthest from melanopsin's sensitivity. That is why a lux meter shows less for it than for the E14, even though at 50 cm both deliver similar radiant power, 1.4 to 2.0 W/m². Lux weights light by the eye's sensitivity to green and undervalues deep red. For the evening, that is exactly what we want: your clock “hears” it even less.

The E14 and GU10 peak at 632 and 633 nm and have a broader warm spectrum, from orange-red to deep red. The GU10 spotlight concentrates its light into a beam, so on the beam axis at 30 cm it reaches almost 3,000 lux. It is built for ceiling and spot fixtures, where it sits farther from your eyes.

Both instruments agreed. The second spectrometer, the UPRtek CV600, confirmed the same spectral shape and peak within 2 to 3 nm, and in the blue region both instruments show only background noise, not light from the bulb.

Want a closer look? The E27 red bulb, the E14 and the GU10 list every measured parameter on their pages. The whole range is in our indoor lighting solutions.

Red night light with motion sensor: why such a narrow spectrum?

The Mitochondriak® red night light with motion sensor shines through six pure red LEDs. Its spectrum peaks at 631 nm and is only 18 nm wide, four times narrower than the bulbs. We measured nothing below 500 nm, and its signal to the body clock is 240× weaker than a white LED.

At 10 to 15 cm it gives 200 to 300 lux, while melanopic EDI stays below 1 lx. For getting up at night, a trip to the bathroom or a child's room, this is exactly the kind of light that leaves intact the darkness your body needs at night.

More on the red night light with motion sensor page.

Do blue light blocking glasses really work? Our spectrometer test

Ours do, and we can show it in numbers. Mitochondriak® blue light blocking glasses let through only 0.0004% of light below 550 nm, which in practice means 100% blocking of blue and green. The signal a white LED sends to your body clock dropped through them by 99.7%, from 618 to 2.1 lx. Red light still passes at 84%, so you see well in the evening.

How we tested the glasses

We placed an ordinary white LED bulb in front of the sensor and measured it once without the glasses and once through their lenses. Without the glasses it gave 1,018 lux at 50 cm and a melanopic EDI of 618 lx. Through the glasses, 210 lux of pure red light remained, and melanopic EDI fell to 2.1 lx.

Why block up to 550 nm, not just blue?

Because melatonin responds to green as well, not only to blue. In a Harvard study, green light at 555 nm suppressed melatonin as strongly as blue light at the start of exposure [R]. Filters that let nothing through below 530 nm kept melatonin in 19 young people at the level of dim light, even under bright light at night. In another experiment at the same 1,300 lux, melatonin fell by 46% with gray glasses and stayed practically unchanged with orange ones.

Clear “blue light” lenses cannot do this; they usually trim only part of the blue. Yellow and orange filters reach further but let green through. Our edge sits at 600 nm. On the spectrometer display you can see it at a glance: white light with its blue peak turns into pure red through our lenses.

Why stylish frames and not wraparound welding-style glasses?

We could have made glasses that seal your eyes off from every side like a welding mask. Only a handful of advanced biohackers would buy them, and they sorted out their evening light at home long ago. We care about most people: those who spend their evenings at a screen, watching TV or reading, and who also care how they look. Glasses you actually wear do more than perfect glasses that stay in a drawer. That is why our glasses have a shape that looks good and covers the eyes from the front and from above.

Why the front and above? Most evening light comes from where we look: the screen, the desk lamp or the ceiling light in front of us. And the angle matters. Japanese researchers shone light of around 10,000 lux into the eyes of 22 volunteers. When it came from above at 28° to the line of sight, it suppressed night-time melatonin by 40%. When it came steeply from above at 55°, only by 8%, because just a third of the light reached the center of the retina [R]. Light from the center of the visual field acts most strongly, and that is exactly where the lenses sit. In another study, light from above, which falls on the lower part of the retina, suppressed night-time melatonin, while the same light from below had the effect of darkness (9 volunteers, 200 lx) [R]. That is also why we avoid ceiling light in the evening.

Glasses do not fully stop light coming from the side, so we pair them with the other half of the evening: dim red light low in the room instead of a bright ceiling light. Together, glasses and red light make the evening dark for your body clock, not for your eyes.

All parameters are on the Mitochondriak® blue light blocking glasses page, and the full range is in our blue light blocking glasses category. How to wear them is covered in our complete guide to blue light blocking glasses, and how to pick a pair for the evening in our guide to the best blue light blocking glasses for evening use.

Incandescent bulb, sunlight and LED: where does the spectrum end?

A classic incandescent bulb with a tungsten filament and the sun both have a continuous spectrum that runs past red into the infrared, while an ordinary white LED ends around 750 nm. See what they have in common? Both shine smoothly, without gaps in the spectrum, and both continue far beyond what the eye can see. Beyond the white LED, there is silence.

Sunlight. At noon on 21 October 2026 we measured 82,212 lux, a color temperature of 5,050 K and color rendering of Ra 99. The reference solar spectrum at the Earth's surface (the ASTM G173 standard) runs from 280 to 4,000 nm, and more than half of its energy, 52%, lies above 700 nm. The near-infrared band IR-A alone (700 to 1,400 nm) carries about 42% of the energy, according to our calculation from this standard. Outside the atmosphere, the solar spectrum reaches even further. Blue light from the sun never travels alone. It always comes with infrared companions.

Warm Spectrum incandescent bulb. Our spectrometer showed a color temperature of 1,965 K, as warm as light at sunset, and color rendering of Ra 96 (red tones R9 86 to 89). The ordinary white LED in the same test reached Ra 82 and an R9 of only 7. The bulb's spectrum rises smoothly from the blue, and 79% of the energy the instrument sees lies between 700 and 900 nm. At 900 nm our chart stops. That is the limit of the instrument, not of the bulb. The shape of the measured curve closely matches the radiation of a filament at about 2,110 K, whose peak lies at 1,370 nm. According to Planck's law, 98% of the energy of such a filament lies above 780 nm. Sunlight at ground level has 43% above 780 nm.

For energy-saving lighting, that is waste. For us Mitochondriaks, it is exactly the part of the sun that is missing indoors. Researchers at University College London describe it the same way: classic incandescent bulbs, like the sun, covered a broad band from roughly 200 to 3,000 nm, while an ordinary LED shines only in the visible range of 400 to 700 nm [R]. In their study with 55 healthy adults, color discrimination worsened after a week under an ordinary LED desk lamp, while it improved when 850 nm infrared light was added. In another study, people working under LED lighting got desk lamps with ordinary 60 W clear incandescent bulbs. After two weeks their perception of color contrast improved, and the improvement lasted another two months (22 people, control group without change) [R]. The same London group measured that infrared light from the sun passes through the entire body, even through an adult's chest. Fire and classic incandescent bulbs carry these long wavelengths; ordinary LEDs do not.

So what follows? We switch the incandescent bulb on during the day, when we are indoors and the sun cannot reach us through windows and walls. It adds the long wavelengths an ordinary LED lacks. In the evening, as darkness falls, red light takes over. The incandescent bulb's signal to the body clock is 2.3× weaker than a white LED, but it is still daylight. More on the Warm Spectrum E27 incandescent bulb page, a comparison in incandescent light bulbs vs LED, and how red and near-infrared light act on cells in photobiomodulation explained.

Are Mitochondriak® red bulbs flicker-free?

Practically yes: our red bulbs are flicker-free. Still, everything that runs on mains power fluctuates a little. The grid alternates at 50 Hz in Europe and 60 Hz in North America, so the power reaching any lamp naturally rises and falls 100 or 120 times per second. The question is not whether a light fluctuates, but by how much.

Two numbers measure exactly that. Percent flicker tells you how far the light dips in one cycle. Flicker index also takes the shape of the wave into account, and 0 means no flicker at all (both are explained in our glossary: flicker). Cheap LED bulbs with a weak driver can drop almost to zero a hundred times a second. That is real flicker: your eye does not see it, but your brain registers it. Our lights behave differently: this is not flicker, just a tiny fluctuation.

The UPRtek CV600 showed a flicker index of 0.01 for the E27, E14 and GU10 bulbs and 0.00 for the red night light. Across repeated readings, percent flicker varied with the tilt of the instrument from 1.2 to 4.7%, mostly around 1 to 3%. The main spectrometer, sampling 50,000 times per second, recorded a flat line with a modulation depth of 0.0% for the red bulbs.

Even a classic incandescent bulb fluctuates on the grid, typically by about 15% on a 50 Hz supply. Our Warm Spectrum E27 measured 8.78% with a flicker index of 0.02. The glowing filament has thermal inertia and has no time to cool down between two waves of current, so it shines steadily. The IEEE 1789 recommendation treats modulation of up to 8% at 100 Hz as low risk (IEEE 1789-2015). At 1.2 to 4.7%, our red lights sit below that limit.

Why do we go into such detail? Many lights are sold with a “flicker-free” label without a single measurement and without explaining what the numbers mean. We measure our lights, check them and explain them. That is the Mitochondriak® difference. We will measure the new generation of our infrared panels the same way.

One practical warning: flicker often appears only with a dimmer. So do not dim our red bulbs; adjust their distance from your eyes by moving the lamp instead. The difference between flicker and pulsation is explained in our glossary: pulsation.

Are red light bulbs monochromatic?

No, and that is a good thing. Monochromatic light has a single wavelength, and only a laser produces it: a diode laser emits in a band just 1 to 2 nm wide. An ordinary colored LED is quasi-monochromatic, with a band tens of nanometers wide. Our measurement confirms it. The red night light with motion sensor shines in a narrow 18 nm band, while the E27, E14 and GU10 red bulbs have a continuous band 74 to 81 nm wide, roughly from 605 to 705 nm, with no blue and no green.

Why not a narrow point of one color? Because we are not after a color, we are after the shape of the spectrum. Our red bulbs are designed to shine where melanopsin is nearly blind and, at the same time, to give enough warm light for you to see contrast and move safely around your home. The orange-red edge of the spectrum turns a red bulb into light for evening life, not a warning lamp.

Just think about where people use red light at night. Astronomers observe the sky by dim red light, because the rods that give us night vision are more than a hundred times less sensitive to red around 620 nm than at their peak, so the eye keeps its dark adaptation. Labs that keep mice and rats have used dim red light at night for decades, because at 600 nm a mouse's eye is about twelve times less sensitive than ours. The same labs also found that bright or all-night red light is still picked up by the animals. For us Mitochondriaks, this leads to a simple rule: in the evening, dim red light for moving around and winding down; at night, darkness.

How do you use light by day, in the evening and at night?

Based on our measurements, circadian lighting at home comes down to three steps: by day, sunlight and a continuous spectrum; in the evening, red light and glasses that block up to 550 nm; at night, darkness and, if needed, a red night light with a motion sensor. Light is not only about whether you can see. It is about what time it tells your body.

1. Day: as much unfiltered sunlight as possible. Indoors, where the sun does not reach, a classic incandescent bulb with its continuous spectrum and infrared part helps. Leave ordinary white LEDs and screens for later.
2. Evening: for the last three hours before bed, red light placed low and away from your eyes, not from the ceiling straight into your face. At a screen, red glasses before bed that block blue and green up to 550 nm. That keeps you below 10 lx melanopic EDI.
3. Night: darkness. If you need to get up, a red night light with a motion sensor that switches on by itself and goes off after 20 seconds.

We keep even red light dim in the evening. In a study with 24 volunteers, six hours of intense red light at 631 nm did not suppress melatonin, yet the eye still responded to it [R]. At the same 40 lux, only blue light lowered night-time melatonin; red did not. Red light, then, does not put you to sleep. It leaves your body the darkness it needs. More on how evening light affects sleep in blue light and sleep, and on melatonin, which our mitochondria also produce, in melatonin: a key hormone made by mitochondria.

Summary

What should you take away from the test? The E27, E14 and GU10 red bulbs shine in the red, from 632 to 656 nm, and have practically zero blue, so in the evening they send your body clock only a fraction of the signal of an ordinary white LED. The red night light with motion sensor is narrower still, with a band of just 18 nm. The glasses stop blue and green up to 550 nm and leave only clean red from a white LED. The incandescent bulb, in turn, is a daytime light: warm, true to color and continuous all the way into the infrared, just like the sun. And none of our lights flicker.

We are not trying to imitate the sun. We are trying to get as close as we can to the natural day our bodies evolved with: by day we add the long wavelengths, and in the evening we take away blue and green. Try it tonight: switch off the white ceiling light three hours before bed, turn on a dim red lamp low in the room and put on the glasses at the screen. For us Mitochondriaks, light is information about time. We don't guess. We measure. The choice is yours.

Frequently asked questions

Do Mitochondriak® red light bulbs emit blue light?

Practically none. Below 500 nm we measured practically 0% of the energy for the E27, E14 and GU10. The measured values of 0.0 to 0.06% correspond to the spectrometer's background noise, not to light from the bulb. Both certified spectrometers, the OHSP-350UVF and the UPRtek CV600, confirmed the same spectral shape.

Do Mitochondriak® red light bulbs flicker?

No, they are flicker-free. The flicker index was 0.01 for the E27, E14 and GU10 and 0.00 for the red night light. Sampling at 50 kHz, the main spectrometer recorded a flat line with a modulation depth of 0.0%. Do not use the bulbs with a dimmer; a dimmer increases flicker.

How much blue and green light do Mitochondriak® blue light blocking glasses let through?

Below 550 nm we measured a transmission of 0.0004%, which means 100% blocking of blue and green. Through the glasses, the melanopic EDI of a white LED fell by 99.7%, from 618 to 2.1 lx. Red light at 630 nm passes at 84%.

How can you tell if blue light blocking glasses actually work?

The most precise way is a spectrometer: measure the same white light without the glasses and through them, as we did. At home, a simple test helps: look through the glasses at a blue and a green area on a screen. If the glasses block up to 550 nm, both areas will look almost black. Our glasses let through only 0.0004% below 550 nm.

Does red light suppress melatonin?

Not in studies with people. Six hours of intense red light at 631 nm did not suppress melatonin in 24 volunteers, and at the same 40 lux only blue light lowered night-time melatonin, red did not. On top of that, our red bulbs send a signal to the body clock 71 to 270 times weaker than a white LED.

What is melanopic EDI, and how much light is too much before bed?

Melanopic EDI tells you how much daytime signal a light sends to your body clock, expressed in lux of daylight (CIE S 026 standard). Experts recommend no more than 10 lx in the evening, starting three hours before bed, and no more than 1 lx during sleep. Our E27 has 0.2 lx at 50 cm.

Why did you measure with two instruments?

To make the test transparent and precise. The certified OHSP-350UVF spectrometer measures 230 to 900 nm; the second certified spectrometer, the UPRtek CV600 with its calibration certificate, measures 380 to 780 nm and flicker. Both showed the same spectral shape and a peak within 2 to 3 nm; small differences in lux came from the instruments sitting side by side.

Sources and references

1. Kubota N. 2022. Effects of different light incident angles via a head-mounted device on the magnitude of nocturnal melatonin suppression in healthy young subjects doi.org
2. Barrett EM. 2026. LED lighting (350-650nm) undermines human visual performance unless supplemented by wider spectra (400-1500nm+) like daylight doi.org
3. Gooley JJ. 2010. Spectral responses of the human circadian system depend on the irradiance and duration of exposure to light doi.org
4. Glickman G. 2003. Inferior retinal light exposure is more effective than superior retinal exposure in suppressing melatonin in humans doi.org
5. Brown TM. 2022. Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults doi.org
6. Ho Mien I. 2014. Effects of exposure to intermittent versus continuous red light on human circadian rhythms, melatonin suppression, and pupillary constriction doi.org
7. Robinson M. 2026. Infrared exposure improves human colour vision undermined by LED light doi.org
8. CIE. 2018. CIE S 026/E:2018 System for Metrology of Optical Radiation for ipRGC-Influenced Responses to Light doi.org