You're in a sleep so deep it's like you don't exist. It's the sleep of infants before they're conceived, dreamless and undisturbable. "Rest" would imply some energy that you've spent previously, but you don't remember anything that could be called "previous"...
But now it's different. There are thoughts passing through your head, where previously there was nothing. There's a sense that you're actually asleep; there are senses at all! There's a feeling of... a pressure against your back. You have a back! You're lying down! Your eyes are closed. You have eyes. You have eyes, and... a responsibility.