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.
It's way more than just that, though. You're also disconnected from your sensory inputs, and furthermore, your conscious experience is interrupted. It's not like you're just in a sensory deprivation tank, because there you'd still experience conscious thought, and the passage of time. It just seems to turn off for a while.
