Sometimes comical but often tragic, somnolence, or sleepinesse takes an important part in our lives. Decisive cause of lethal highway accidents, drowsiness invites itself in our work. What happens with our brain? Can we master sleepiness ? By working on the sleep and especially on the functioning of awakening, researchers try to understand the biological and environmental mechanisms that maintain human beings at the top of their capacities. What if drowsiness was there to prove that we are not machines ?