Seems like a lot of work just to sit in a dark closet. My brain would just start thinking about all the laundry I need to fold in there instead of getting calm.
Turned my old coat closet into a makeup station last spring. Put up a fold down desk for my palettes and hung a dollar store mirror on the back of the door. Stashed all my brushes in cleaned out jam jars. It's cramped but having my own little zone changed everything.