peace
hmm. i don't think we go anywhere.
when we sleep we are in restmode, we are unconscious. the body repairs itself, the more you are physically active the more rest needed.
the same goes for the brain.
39:42 God takes the person when it dies, and during their sleep. He then keeps those that have been overtaken by death, and He sends the others back until a predetermined time. In that are signs for a people who will think.
nafs
Soul/spirit, the vital principle, intellect/reason/mind, inner desire or feeling, knowledge, pride, self-magnification, a state where there is ample scope for action, 'willingly' when used as adverb, nafs - soul of discrimination (mental) and ruh - soul of breath (physical), oneself/itself, whole, essential constituent, reality, sometimes ghayb and nafs are synonymous, a person/being/individual, quantity, man, life, soul + body, life-blood, body, contention/thought/face/substance, heart, stomach, gulp, drought.