The Great Blue Light Panic Keeping Some Folks Awake
If you read alarmist comments on the inter-webs about the dreaded “Blue Light Hazard”, you may come away thinking that your TV, tablet, phone, and LED bedside lights are depriving you of sleep. Yes, the spectral power content, including blue light, can produce amplified melatonin suppression that can indeed disrupt your ability to fall asleep. And, yes, LED lights and many LED based displays do produce blue light at the wavelengths of greatest concern. We’ve been all over this, like here, and there have been thousands of other discussions on this everywhere, including in mainstream media – which for the most part get it all wrong.
The first thing everyone needs to understand, is that there is no universal standard of exposure (high or low) established for circadian effecting light, so there are actually no solid foundations on which to base concerns or alarm. However, the LRC (Lighting Research Center), and WELL Buildings have set out a few guidelines that can be used to quantify and evaluate conditions. The metrics used by these entities include Circadian Stimulus (CS) by the LRC, which sets fort a minimum of 0.3 for active hours to produce desirable melatonin supression, with a maximum of 0.3 for periods prior to sleep cycles. Melanopic Lux, set out by by WELL, established a desired minimum of 200 for waking periods, and a maximum of 50 for pre-sleep periods.
The calculations for Melopic Lux and Circadian Stimulus include the entire range of light that has an impact on physiologic response – which is centered on blue light between 430 and 480nm. Thus, they are both inclusive of the light everyone appears so concerned with. Further, meters that produce outputs with these metrics, capture that same blue light, and utilize algorithms to establish the Melopic Lux and CS value for the source being measured.
With this in mind, most of the actual lighting scientists, and those doing research on visual sciences, have expressed that the concerns over blue light content are being addressed inappropriately. At very high retinal levels, yes, blue light can cause severe damage to retinal cells. At high illuminance levels, sources containing high levels of melanopic light will induce undesirable effects on circadian cycles. However, this does not necessarily translate to what is experienced in the real world. What is important, is to understand how much light is available to the eye of the observer, in actual conditions, and of what character. Stating that all blue light is bad, and should be avoided at all costs, is overly simplistic and fallacious. Blue light is in all light sources we work and live under, it cannot be avoided. Sunlight has more blue light as a portion of total illuminance than any artificial source (including LEDs), with moonlight being even higher. A blue background on a computer screen is seen as blue, because it emits blue light. The real issue is to understand what light we are exposed to, and what its spectral content is, at whatever intensity we are seeing at the eye itself. That is what the CS and Melanopic Lux metrics are intended to address, in both overall brightness as well as effect on physiology.
The overwhelming mass of public discourse (and hysteria) on blue light focuses on the alignment of blue light with circadian response, with little or no mention of exposure levels. This is like saying that since exposure to water can cause drowning, drinking water exposes us to risk of drowning. The water is not the issue, it is a matter of quantities of exposure and conditions involved. Drinking a glass of cold water over a period of a few minutes is significantly different that being submerged in a large body of cold water with a concrete block tied to your ankles. One will sate your thirst, the other will likely cause hypothermia and possibly drowning. Controlled amounts of blue light are normal and harmless. Extreme exposures of retinal cells to blue light lasers will cause cell death. In the real world, 80% (or more) of the noise surrounding blue light exposure and its effects on human sleep, is by marketers selling product promising to mitigate the dangers published by the very same marketers.
In order to demonstrate real world exposures, I took a few measurements around my own working and living existence, to see where things stood. Measurements for this purpose are taken at eye level, with the meter pointing outward at the normal viewing angle for the space/environment being evaluated. Horizontal illuminance is irrelevant in this evaluation. Here are the results:
Note that in these environments, I have put in place lighting components to increase the CS and Melanopic Lux values at work, but have made no effort at home to reduce them.
As you can see, within the recommendations of the LRC and WELL, I am working under what would be considered good light at work, and well under the maximums suggested at home, for pre-sleep cycles.
A great deal has been written about blue light from smart phone and tablets. So, I took two trusty devices into a dark room for evaluation, and found the following:
Within the recommendations of the LRC and the WELL Buildings standards, neither device presents a specific issue with circadian effect or disruption. And, important to note, these were not typical color displays, they were white screens set at a relatively high illuminance setting. Also noteworthy, is that these measurements were taken at a distance of 4″, which is rather close for most average sighted individuals. In the prior result, viewing a dimmed tablet from a more reasonable 20″ distance, produced levels were even lower.
Based on all of this, I am not seeing anywhere that blue light (read circadian disruption) from devices is a significant enough issue to warrant all of the noise surrounding it – at least from a circadian disruption perspective. I propose that any article, comment, or post offering opinion about the hazards of blue light, that do not include specific data points on exposure levels and exposure timing, can be dismissed out of hand. Broad generalization that use call to authority fallacy based on mentions of lab studies that utilize extreme measures, extreme illuminance levels, or even laser sources to investigate blue light impact on tissues or physiology, can also be ignored. A recent broo ha ha surrounding a study that exposed retinal cells to blue lasers to evaluate cell damage, blown out of proportion as proof that LED displays are destroying human vision, is a perfect example of information best tossed in the “whatever” bin.
On the topic of eye safety, I explore that in greater detail on my other site, which covers the more detrimental UV spectrum (<400nm).
Back to the Bedroom
Keep in mind that the human body recovers from exposure to melatonin suppression in a time period of between 45 and 60 minutes. For this reason, most experts on this topic address the period of 1 to 2 hours prior to the desired sleeping time. Light content outside this time period is irrelevant to Melatonin suppression mitigation.
Within 1-2 hours, illuminance levels below 50lux will likely not produce any significant blue light or effect on sleep behavior, whether from viewing screens or displays, or room lighting – unless the only source of light is just blue. For normal white light environments in sleeping areas, the lower the light level the better.
I personally believe that the effect of goofing around with a smart device or watching television produces more sleep interrupting impact from mental stimulation due to content than the light they emit. While very young viewers may experience a reduction in serum melatonin blood levels (yet still sleep constantly), adults past the age of 30 will likely find that blue light is less an issue than the mental activity involved in watching a program, playing a game, scanning messages, or falling into a Pinterest black hole.
That said, I suggest the following for bedroom environments:
- Keep illuminance levels as low as you can tolerate. 30 lux is the most anyone will ever need to do what is done in bedrooms… and maybe too much depending on the appearance of one’s bed-fellows. If you don’t have a meter to measure light levels, download an app for one and use that. Measure the light from where your eyes are, with the meter facing outward.
- Adjust TV screen brightness level to the lowest possible, or turn it off at lest 45 minutes prior to desired sleep periods. Don’t watch anything interesting while attempting to sleep. Listen to music or white noise in stead. Avoid anything that is of interest, that causes any response or interest. The blue in the TV screen is not the issue, the interest in content is.
- Leave the smart devices, phones and tablets off, or at a low brightness level, and only for what little time it takes to be certain that there is no emergency in the world you need to address immediately. Otherwise, playing games, watching videos, surfing, etc… is not going to be conducive to sleep, even if your device has no blue light emission.
- Paint interior walls a neutral color with a reflectance of less than 50%. This will improve the overall feeling of darkness and quiet. Pay attention to all aspects of the space that might interrupt sleep, from acoustic to temperature, to spooky shadows that move when the wind blows.
- Install blackout curtains if there is any light intrusion from exterior lighting (easy way), or work diligently with city, county or state legislative bodies to change their specification for street/area lighting to keep whatever light they are maintaining or installing from entering your sleep areas (much harder way)
- While I personally use LEDs in my bedroom lighting, anyone concerned at all with this should just avoid them. The amount of energy being saved over an hour each night is not significant. Incandescent lamps are still a good choice for the bedroom. Not only does the spectral energy address any blue light concerns, it makes skin tones nicer for those non-sleeping activities (nudge nudge wink wink).
- For those who read in bed to go to sleep, adding task lighting with a narrow distribution to avoid disturbing others is advisable. However, reading in bed is the same issue as playing with electronic devices, as light reflected from the page is no different than light emitted from a display. An LED reading light is going to produce the same effect as an LED display. Either keep levels as low as possible, or find a better approach to inducing sleep not involving staying awake.
And About More
None of this addresses any concerns about white and blue light impact on our natural surroundings and wildlife. None of this addresses the ongoing debate about street lighting. There is a reason for that. Most folks do not have street lights in their bedrooms, nor do they harbor wildlife (other than the human activities of that kind). I have also not addressed the topic of circadian light and other health issues, such as cancer rates etc.. as that research is ongoing and yet to come to a conclusion relevant to the topic of creating a better sleep space in our homes.
With all this considered, the best approach to getting a better sleep is to set up an environment that is conducive to sleep, establish an approach to the time prior to entering the sleep environment… and ignoring all the hysterics attempting to make you lose sleep based on assertions that are either intent on getting you to buy some product, or incite you to join someone’s cause against an invisible enemy conspiring to destroy you through beaming rays of dangerous light into your eyes. Night, night…