I want to know that does the soul of a person departs the body at the time of sleep and returns at the time of awakening?
Also, do the angels ask for permission of Allah before they bring back the soul to the person?

Yes it has been said in the tradition of Ma’soomin (a.s) that the sleep is the sister of death and our soul departs from our body at the time of sleep but this de attachment of the soul is short and person gets another life with the command of Allah while after death they separate from earth other for forever.