text: Why do we block blue light? - A simplified explanation
  More and more articles, research, and anecdotes are arriving every day about the dangers of blue light! Large cell phone companies now build blue light filters and night-shift modes in their phones, recognizing this issue.
  Blue light exposure is now linked to everything from eye degeneration to cancer. This simplified science-backed explanation shows how.
  The Danger Zone:
  There are two primary danger zones associated with blue light. High energy Blue Light Hazard as defined by the IEC (International Electrotechnical Commission) (1). This commission set out a standard to regulate the LED industry for blue light hazard emissions. This region defines where damage can be caused by wavelengths of blue light as a function of intensity and exposure. Prolonged exposure implies eye deterioration, macular degeneration, and other eye damage.
  The second region is the melatonin suppression region(2). In the evening if we are exposed to bright blue (or green) lights, our body will reduce the natural production of melatonin. Melatonin is not only critical as a sleep hormone, but as an antioxidant for health. Suppressing melatonin leads to disrupted sleep and reduced ability to fight off disease.
  Here we see the Blue Hazard light range with the peak sensitivity at 435-440nm, but it extends on to cover all of blue up to 500nm.
  The melationin suppression range peaks at around 464nm with the major suppression between 446-477nm. However it extends all the way to the Green/Yellow part of the spectrum to around 570nm.
  The Main Offenders:
  Bright white lights emitted from computers, cell phones, LED lights, and fluorescent lights contains strong peaks of blue. The higher the color temperature (K, or Kelvin), the stronger the peak of blue coming from the light.
  See here the typical white LED has a peak blue wavelength at the cross-section of both danger zones! For this example the peak is at about 452nm.
  This becomes especially hazardous in nighttime or low light conditions. Our iris will be wider to receive more light, and the harsh blue will be allowed in with our eyes unable to adjust fast enough for protection.
  Man Versus Nature:
  It is true that the most intense source of blue light is indeed the SUN! However, we do not want or need to block sunlight. Why? The sun is balanced with the red and infrared wavelengths for healing and protection. When combined with blue, it washes out much of the hazards from above.
  See below for a comparison between an LED and typical Sunlight.
  What the LED is missing is A LOT of red and practically no infrared, and we know that Sunlight extends into the invisible infrared range. In fact, about 50% of the sunlight is infrared!
  In industry we wear Personal Protective Equipment (PPE) to protect us from hazards. Here is no different, we can wear blue blocking glasses or install blue light filters to reduce the effect.
  However, depending on the time of the day and the task being performed then different levels of light blocking may be required, if any.
  For optimal eye health, block or reduce the main peak of LED blue light of at least 455nm, which covers the main blue hazard zone.
  For optimal sleep, block at least up to 510nm in the evenings, and even block up to 550nm+ just before sleep. Try to block the majority of the melationin suppression zone.
  PPE is typically the last line of defense! To control your biology, it would be best to replace artificial lighting with low color temperature bulbs, no blue, or even red lights.
  As we know red and near-infrared light stimulates mitochondrial function, regrowth, and repair. When exposed to balanced spectrum of light from the sun, the blue light is a non-issue.
  GembaRed lights also offer a simple way to help balance your blue light exposure from the day.
  (1) IEC 62471:2006