Patanjali says there is not much difference between sushupti, dreamless sleep, and samadhi, the ultimate state of buddhahood -- not much difference, although there is a difference. The difference is that of consciousness. In dreamless sleep you are unconscious, in samadhi you are conscious, but the state is the same. You move into God, you move into the universal center. You disappear from the circumference and you go to the center. And just that contact with the center so rejuvenates you.