Does the room have an overhead light or any other light source?

I would put a fixture with brighter lights over the vanity portion only. If there is other lighting or a window, that might be enough.

If there is no lighting at all in the room, and no window, I would put one fixture above the vanity and another one (not necessarily identical) at the same height on the wall opposite the toilet. I am guessing the tub is next to the toilet, in which case, the person using the shower/tub will need light, too.

There are no windows or overhead lights. The toilet and sink are on wall with mirror to the left, and shower will be at end with inside light. Thank you for your suggestion to put another light on wall opposite the toilet. I appreciate the advice!

My pleasure.