After heading up a small spiral staircase just behind the professor's desk in their classroom, you can find the office to the Potion Master which is currently Professor Alyss Mitchell-Anderson's
Office. When you look around, you can quickly observe that the lanterns of light that hang along the walls have nearly no effect on the commonly dark room. Since it's located in the Dungeons, it doesn't have any windows or any natural source of light to brighten it up. However, the several plants that fill the room give some sort of life to it (and successfully balances out the shelves of potions and their ingredients that are located behind the desk in the center of the room).