When babies are asleep, they often look at peace with themselves, but dreams and discomforts can still manifest though sounds and movements.
When you come to savasana at the end of a Yoga session, the teacher asks you to make your self comfortable and to choose not to move anymore until the end of it.
I used to guide my students into relaxation and to accompany them as they would be in Yoga Nidra (the deep sleep). I found that they became dependent on my voice and Idecided they needed to gain autonomy to really benefits from their relaxation.
Richard Agar-Ward, a Senior Iyengar teacher , taught us recently to observe the complete release of the abdomen when the feet and legs are rolling out in the posture of the corpse. He reminded us than dead people are only really dead, not when their heart stops beating, but when their guts finally give in. This made me more aware of the complete abandonment of my legs and lower abdomen in savasana