A soldier told me that he saw some of his compatriots falling asleep during battle.
I have had trouble with fear of sleeping. Driving when tired is bad for habit-forming, but then I fell asleep when walking between bathroom and bedroom. I turned out the light, and fell down the stairs between the rooms. I remember thinking, as in a dream, that I didn't remember the bedroom having a step down, and that I should try to land on the bed, throwing myself forward. Next, I had a disaster from being woken up at just the wrong stage of sleep, and was almost completely disoriented for two weeks. That only added to the fear of falling asleep.