When using it for the brain, are there big differences between red vs. near-infrared light? And does the light penetrate through hair and skull? NIR will get through the skull more effectively, so for the brain specifically, near-infrared is going to be superior. Neither near-infrared nor red light will penetrate effectively through hair, so you don’t want to shine it on the hairy parts of your head, but the forehead, back of the neck, and ear areas are all good.
