Some bulbs (more properly called "lamps") are of a lower CRI AND emit no UV. The tradeoff is the loss of the FULL spectrum, but these BROAD spectrum lights are brighter, to compensate. Some experts think that's the better tradeoff, and that the brightness is more important the the blue color lost in most lighting that is not full-spectrum.
Some SAD lightboxes come with a UV-blocking diffuser. My glasses already have UV coating, so I'm going with what I have for now, but we are going to also get a pair of the type mentioned above and see what the difference actually is.
Some folks also say there are two types of SAD, which require different timing. One type needs early-morning light, and the other needs 3-7PM light. Some folks find a mix of the two works best for them; you have to see what's working and refine it for yourself.
This thread is not intended to replace one's own research and medical consulation. There are a lot of things to learn about all this. But-- if you live with a sufferer, try lighting them up for a day or two before asking them to read all the stuff available. :~) So they can comprehend it. :~)