How to ensure the astronauts sleep?

In one of the laboratories of the German volunteers pay for what they help to explore one of the most serious problems of space travel: how to ensure astronauts have the best sleep at night? Underground research laboratory surrounded by a forest near the German Cologne. The walls are white, softly lit, has no Windows and only a few pictures. In the room there is a bed, a computer, and hangs a disturbing painting with unearthly landscape, with giant flower of a plant and the strange futuristic space land. On the ceiling fixed camera that tracks every step.