। ॥ ९५७ ॥
In plain words
When all objective mental activities cease for him and he abides purely in the contemplation of his absolute isolation, attaining supreme oneness with pure awareness, this is known as the deep-sleep-in-deep-sleep state.
Close to the Sanskrit
The seen-intellect-modification of this, contemplation of absolute isolation, supreme attainment of oneness with consciousness—deep sleep-deep sleep is declared.