Mirrors are necessary in bedrooms for dressing, assessorizing etc., but like Jean I’m not sure how useful a mirror behind a lamp over a nightstand would be. My bedroom is rather small, 13x15, so I replaced the bifold doors on the 2 closets ( both on the same wall) with mirror doors. It really enlarges the room and is great for checking hemlines etc.

I have oval mirrors over my nightstands. No they really don't serve any purpose other than they are pretty. I have mine a couple inches below the lamp shade so they reflect the light. As far as size that I don't know. I saw these, liked them, bought them.

I'm seeing this a lot as I browse bedroom pics for inspo. Am planning on doing the same in my bedroom. Glad you asked the question, Alexandra. Someone might have pointers about scale and proportions.