I suffer insomnia sometimes. When that happens, I would lie on my bed and find that my mind is active. As hours go on, I would seem like falling into dreams, only to wake up later. The process of falling into dreams and wake up with a lingering memory of the dream would repeat many times into the night.
When the next day comes, I would find that I am tired and my mind is not as sharp as the normal days.
So I wonder when that happens, do I really have enough rest for the night? Am I really sleeping?