I have posted related articles last year, and as I can recall, the
favored LED wavelengths are 680, 730 and 880 nM.
880 nM IR is common (see above post) 680 is deep red, 730 is near-IR. I have built up a unit with a mix of 635, 660 and 880
nM red and IR LEDs, and it does seem to help, but then it could be that "placebo effect" working. At worst, it will have no effect, at best it may really heal. If you do decide to try to home-brew something for this, play it safe with electricity, power it with batteries (preferred) or a wall-wart that is UL rated.
I was trying it to accelerate the healing of a serious knee injury, it does seem to alleviate the pain, and supposedly encourages better blood flow in the area, according to an article on this from NASA a couple years ago.
/ed B in NH