The only state which truly exists is the state of wakeful sleep, (jagrat-sushupti) that is, the state in which we remain ever awake to the real self and ever asleep to the unreal world of multiplicity.
The scriptures refer to this one truly existing state as the ‘fourth’ (turiya) only for the sake of those who experience the unreal three states, and only with the intention of making them understand that it is something quite different from those other three states. But when this real state is experienced, the unreal three states will be found to be completely non-existent, and hence it will be known that this real state is not really the fourth state but the only existing state. For this reason the scriptures also refer to this truly existing state as ‘that which transcends the fourth’ (turiyatita).
~~I don't know who wrote this