Consciousness is often said to disappear in deep, dreamless sleep. We argue that this assumption is oversimplified. Unless dreamless sleep is defined as unconscious from the outset there are good empirical and theoretical reasons for saying that a range of different types of sleep experience, some of which are distinct from dreaming, can occur in all stages of sleep.
I mean, without defining what the self is and consciousness, it's difficult to even define what death is from a consciousness point of view. A living meat bag doesn't require brain activity either. There's a whole range of things. So even assuming we have a good meaning of "death" is oversimplifying things.