I took this picture in one of the dormitories in the Kamp Vught concentration camp. Each one of these long, two-tier wooden constructions slept 60 prisoners and the room contains several of them.
Can you imagine how humid the air would be with so many people sleeping in such a confined space? And think how much carbon dioxide there would be in the room. For these and many other reasons a dormitory like this would not be a healthy place to sleep. (Kamp Vught: A Dutch National Monument with a Sad History)