Lots of good answers already in this thread, so just pitching a couple of “not what you asked for but maybe interesting” thoughts: Have you tried CFL lightbulbs? Those don’t flicker and should be available in a wide range of temperatures. Regarding the headaches, imho it’s more likely to do with blue light/color temperature than flickering, unless it’s severe enough you can notice it even if just barely. In that case, maybe look into glasses with blue light filters, helped me a lot with screens and indoor lighting

It is so much worse. Humanfacing