Some more interesting perspectives on Death, Sleep and Soul along with their relationships. Here is another quote that explains this issue further.
"Death and Sleep:
Body is a home for the soul. The soul departs at sleep and returns when it is time to get up. A dead body is like a collapsed house. The soul does not come back to it, till the moment it is recreated. This is what this verse decrees: “Allah takes the souls at the time of death, and takes those that do not die during their sleep. He withholds those for whom He decreed death and sends the others back for an appointed term.” (Az-Zumar/The Throngs 39:42)
Both the words ‘death = mawt’ and ‘taking (the soul) = wafaat’ are mentioned in this verse. The word ‘anfus (sing. nafs)’ in this case is both the subject of the verb “يتوفي= yatawaffa = taking (the soul) “, and the object that is affected by “موت=mawt = death” and “منام=manam = sleep”. According to this, there are two intellects (two nafs) in a person; the one that is taken (made wafaat), and the one that sleeps every day and dies when the time comes. With a careful study of the relations between the verses, it is noticed that the intellect (nafs) that sleeps and dies is ‘the body’, while the one that is taken (made wafaat) is ‘the soul’.
The root of the word ‘wafaat’ is ‘wafa=وفى’. The Arabic word wafa stands for ‘accomplishment’. To cause to wafaat, which is توفي’=tawaffi’, is ‘causing to have something accomplished’. Since there is nothing the soul will do during sleep or after death, Allah extracts the soul from the body in both cases.موت=mawt is the loss of vitality; death."
"Death and Sleep:
Body is a home for the soul. The soul departs at sleep and returns when it is time to get up. A dead body is like a collapsed house. The soul does not come back to it, till the moment it is recreated. This is what this verse decrees: “Allah takes the souls at the time of death, and takes those that do not die during their sleep. He withholds those for whom He decreed death and sends the others back for an appointed term.” (Az-Zumar/The Throngs 39:42)
Both the words ‘death = mawt’ and ‘taking (the soul) = wafaat’ are mentioned in this verse. The word ‘anfus (sing. nafs)’ in this case is both the subject of the verb “يتوفي= yatawaffa = taking (the soul) “, and the object that is affected by “موت=mawt = death” and “منام=manam = sleep”. According to this, there are two intellects (two nafs) in a person; the one that is taken (made wafaat), and the one that sleeps every day and dies when the time comes. With a careful study of the relations between the verses, it is noticed that the intellect (nafs) that sleeps and dies is ‘the body’, while the one that is taken (made wafaat) is ‘the soul’.
The root of the word ‘wafaat’ is ‘wafa=وفى’. The Arabic word wafa stands for ‘accomplishment’. To cause to wafaat, which is توفي’=tawaffi’, is ‘causing to have something accomplished’. Since there is nothing the soul will do during sleep or after death, Allah extracts the soul from the body in both cases.موت=mawt is the loss of vitality; death."