Light leaking in/out.

Alright, so I just hooked up my 400 watt HPS light today. The problem I am having is that it is in my room's closet. I want it in here for safety etc. I have people over my house all the time, and NO ONE comes in my room that the plants are growing in.

My problem is, my room will simply not be dark, is this a problem im going to have to live with? Ie with all my lights off, it still shines out of my closet like I have a artificial sun in my room. My room is light proof, however I would like to light proof my closet so no light escape out, or if anything very minimal light.

Anyone have any suggestions on what to use for this? a better detailed description, this is not a walk in closet. its a normal closet that basicially branches off like a new room. but the doors are folding aluminum with slits from top to bottom. and half a inch of space between the floor/ceiling and the closet door.