Can leaving the vanity mirror light on in a car drain the battery?

Can leaving the vanity mirror light on in a car drain the battery?
Yes, definitely! I have a 2010 Toyota Rav 4 with very low miles that suddenly had dead batteries after sitting only 1-2 days. Putting a new battery in the car did not solve the problem.
I had the car towed to my Toyota dealer, who could find nothing wrong with the car after testing it for a week. They charged the battery, and I drove it home.
Because of the heat of summer, I placed sunshades in the windshield and noticed for the first time when I put the driver-side visor down, that the vanity mirror light came on. The cover over the mirror was open, so I closed it. The light went off. I have not had any problems since.
I confirmed with a mechanic that the vanity mirror light could indeed drain the battery in 1-2 days. LESSON LEARNED