Help with Light Height

I have a 4x4x6 room with a 400w MH. Its not vented cause the room is always at 76 degrees. Day and 70 at night. How close can i bring the light to the plants? Its all the way at the top of the tent. Maybe 3 1/2 feet away right now.

Thanks in advance!!

If its too hot for your hand, its too hot for your plants is my rule of thumb, the closer the better i say

put your hand under the light above the plants, if its too hot for your hand its too hot for the plants, a good foot or so from the top of the plants should do, just check everyday for growth and make sure its not getting to hot at the top of the plants and youll be good.

thanks just moved it. There was no stretching at all with them just wondering if The light getting close would help.