That almost sounds like riddle, when does a man sleep, but not dream? Of course, the answer would have to be death, which I've never really been able to fully wrap my head around. Perhaps death is just a deep sleep from which you never wake. Do other languages prefer the death/sleep metaphor?
"Maybe it's just me, but what I consider to be my dreams aren't what happens when I'm asleep. My true inner dreams come out in the in between minutes when my eyes are shut and I'm still awake. My deepest desires and my darkest fears, everything I've ever done wrong, and everyone I've ever loved. Past glories, forgotten friends, all that I've ever done, and all that I plan to do, in those few minutes. The darkest nightmares that could only occur while awake, because the unconscious mind couldn't imagine such things, tempered by the sweet remembrances of home from long ago, and the sweet touch of lips against mine. Finally, nothing is left except for the inevitable escape into slumber.
When I wake up in the morning, I remember my "dreams", how the great times were only good, and the horrible times weren't that bad. Dreams are the past and the future, but today is the present." -- excerpt from the autobiography of Seanahan