"I'm trapped in a cube, narrow but comfortable." Babies have memories and thoughts in their mothers' bellies.
This kind of memory is related to external interference and fear.
It's easy to fall asleep by putting the baby to sleep and patting him rhythmically, because he is used to the sound of his mother's heart beating in his stomach and patting him in a similar environment, so it's easier for the baby to relax and fall asleep when he feels safe.