I have just conducted a fascinating correspondence with an eminent translator of German poetry. Our debate has centred on the need for a raw native English word to express the state of Hypnagogia. Ours was a discussion on the problem of translating into English the indeterminate state between wakefulness and unwakefulness ... the brink of sleep, as it were. Sleep-brink is a fresh construction but clumsy. Reverie does not wholly answer this want because it implies consciousness. What is wanted in English is a Nietzschean compressed neologism ... but what?
I am reminded of Robert Graves and his exquisite lines ...
Forget the rest: my heart is true
And in its waking thought of you
Gives the same wild and sudden leap
That jerks it from the brink of sleep.
My distinguished correspondent refers to unsleep as an inconstant state. So unsleeping sleep or sleeping unsleep might answer this want!