By now, most of us have heard how terrible LED lightbulbs (and “screens”) are with the “blue light” they output. You may have seen some spectrum analysis graphics (probably mostly copy and pasted from the same sources).
Here I’d like to present some original research (my own test results).
First we have a standard old Sylvania 60 watt incandescent light bulb (you know, the kind we grew up with).
We can see that a lot of the energy is infrared – heat that we can’t see. Inefficient as lighting but healthy.
Next we have a typical modern 10 watt (“100 watt equivalent”) LED bulb.
Here we can see the spike of blue light but surprisingly we have a dominance of a wide range of spectrum centered around orange (601 nm). Maybe not as bad for you as you have been told?
Next we have an old 25 watt clear red GE incandescent bulb.
Again we see a lot of energy “wasted” as heat in the infrared wavelengths and we see the light as very red as the only wavelengths it puts out in the visible spectrum are essentially red.
Next we have a Red LED (8 watts) bulb. Note: this is just a cheap bulb, not one marketed specifically for red light therapy.
Here we see an “energy efficient” production of essentially just light in the red spectrum. Nothing “wasted” as infrared heat.
Next is a small 7 watt “Grow light” (marketed to help your plants grow).
With this bulb, we get two very narrow spikes of light. One in the blue light spectrum and the other in the red light spectrum. Nothing “wasted” as infrared heat.
Next we have a larger “grow light” (unfortunately it’s unmarked so I have no specifications for it - out of curiosity I measured it and found it uses 11 watts of energy).
This one is intriguing with a wider blue spike and a wider red spike but also with a curious bit of infrared!
A point I’d like to make is that it seems we underestimate the health benefits and our natural exposure to heat (infrared light). So when we talk about “Red Light Therapy” we may find that the bulk of the benefit is actually from infrared wavelengths.