Well, millions of people sleep on the things every night, and they're not going up in flames... Just don't smoke or set off any fireworks in the room. If you can get some ceiling tiles cheaply (or, better yet, for free) do that - that is a much better idea. But they might be harder to find. Most ceiling tiles from remodels either are put in storage for later use or go right into the dumpster because they're old or damaged.