Oddbean new post about login | logout https://scholar.google.com/scholar?q=670nm+health+studies&hl=en&as_sdt=0&as_vis=1&oi=scholart Take a spin and read some of the studies, seems skin and eye benefits in the ~650nm range. You can have warm light 2700K-3000K that is not in the 600-700nm range and does not seem to show benefit
If any specific wavelengths matter, LEDs will either have to produce all of those or there's no alternative to an incandescent light. But I suspect the human genome mostly developed absent any artificial light, including fire, so it's probably healthiest to get out during the day and sleep at night. It's not the most productive, especially where nights are long but that's kind of what we are built for.
No doubt getting out in real sunlight is best, we are in full agreement on that