@Belial phil,
If I might make a comment here. Considering we can only observe death, no one can possibly know what death is, for certain. Most are so steeped in what lies beyond, and that is what serves as the catalyst that spurs our interest. Now if you don't mind, let me stop time for a moment and put it in "limbo" which I think is what sleep and death are.
One is for the soul, one is what that soul has experienced as we dream and imagine what those experiences have been; are the "sweet dreams" coming from a peaceful nights sleep as the soul is no longer tormented, or are they turbulent, tossing and turning as the soul is not so peaceful? I think as long as we interpret death as an end or finite, we create that hell that is represent in that tossing and turning created by that very fear of what lies beyond and usher in that death for those experiences, past and present that are, more or less, beating us up saying "snap out of it". Death is reaching a point of no return and the "soul snaps out" and goes in for an "overhaul" so to speak, which can't be defined so let's just call it limbo.
How long one stays in limbo depends on how much damage has been done and whether one is the cause or affect of those damages as it relates to others. If one is truly a victim and death was affected by others they remain in protective custody as those who were not go right back until they do finally do snap out of it and understand life is truly eternal and what goes around truly does come around as they are place in that state of being in which they can no longer cause that damage and become a victim such as those in which their greed for life imposed on others as they walk in those very same shoes.
The body does not have to be "physically dead" to experience death for there are those states of protective custody here that serve that purpose such as what can be defined as coma of any other term that indicates a detachment from this reality.
When we think, it is our soul talking to us. When the mind is at rest we don't think so much and a state of peace ensues. When we think out loud, such as every one does when they are alone (though many will not admit that they do) it is the soul putting emphasis on something we did, should have done, or something we didn't do. When one truly thinks about it, that is exactly what one does when they are "talking to themselves".
Now let's dig a little deeper and observe those who care not if they are alone when they talk to themselves for they are more detached and virtually pay no attention to others even being around such as might be observed in those mental states we consider "ill"; such as more severe degrees of autism, schizophrenia, turrets syndrome. ADD and ADHD are the beginning stages of such detachment as it indicates a difficult time devoting attention to this reality and it's dictates.
They also are in "protective custody" and serve a burden to this reality teaching us all a lesson that will eventually allow us all to "SNAP OUT OF IT".
Deep sleep or REM state is that dream state and those rapid eye movements are indications of how much the soul is going through. Now the only reason we go into deep sleep is because we truly need the rest and the REM is indicating it's effort to catch up as the mind assimilates all that has been experienced. In other words we are experiencing far to much to fast an we "wear out". Such as can be indicated when anyone says, "I have a lot on my mind". What a pity, IMO. If people only knew how so very "hunky dory" everything is when the mind is at peace as they will eventually learn they will not need as much sleep as they once needed as being awake and conscious can be a very pleasant and peaceful experience and it is only our thoughts that disturb it causing us to need rest from it all. I am of the opinion death is no different; we just wear out. The body doesn't die, we kill it and the soul goes in to get another one. Let's hope yours is a newer one that is incapable of becoming a lemon.
That's for your attention, I hope it tied up a loose end for you.
William