He seemed now to be in a natural sleep.

During early parts of natural sleep, an individual is difficult to arouse.

Immediately afterward, he slipped away into a more natural sleep.

"He seems to be much better, but this is not a natural sleep," said the robot.

A perfectly natural sleep that I had nothing to do with.

Then he fell into what seemed a natural and peaceful sleep.

The boy passed from his trance directly into a natural sleep.

She felt herself drifting into a deeper, more natural sleep.

I could do with some natural sleep,' he said at last, 'but I've got to get the fleet moving first.

"And from the way her hand is thrown out to the side it looks as though she had fallen into a deep, natural sleep."