Is it the problem with the mattress or the room being too bright? For some people sleep just comes so naturally while for others, they even need to resort to taking sleeping pills. I find that when I am hungry, I can never fall off to sleep even if I am dead tired and sleepy. Food somehow comforts me and makes me sleepy. Even if I slept well, and after a light lunch, I start to feel sleepy while doing work or anything.