। - ॥ ५८१ ॥
In plain words
When everything dissolves into stillness in deep sleep, nothing appears except a blank void. Yet that void is not the true Self; rather, beyond it shines the living reality known directly as the ātman.
Close to the Sanskrit
In the time of deep sleep when the whole universe is dissolved, nothing other than the void is found here. But the void is the non-self; no other transcendent entity named as the Self is experienced as the reality.