Sentence:  For many <WSD>nights</WSD> afterward , the idea of her having been so close to me in that imagined bed would return and fill me with obscure and painful desires , would cause me to lie awake in shame , tossing with irresolution , longing to fall into a deep sleep . 
Meaning of the word marked with <WSD> tags:  the time after sunset and before sunrise while it is dark outside