stepmother (from the Hansel and Gretel poems)

I like the rhythm of this and most of the wording. "unspent" seems a stretch to be unconventional, and I don't think it works well. One doesn't 'spend' sleep, so 'uspending' doesn't fit; and given that unspending could be considered as 'saving (money)' or even 'earning' (opposite of spend), it hints at something positive, which I'm sure is not your intention. "Undid" or, even better, "harrowed" would be better choices, and there are others.
I like the "...sister wept..." line the best, and also the shortening of "amongst", which keeps the rhythm there from hiccupping.

Alcuin