Ruth consciously told her brain to not fell asleep. She had many thoughts on her mind, and sleeping defenselessly in a company of a stranger even though he appeared to be friendly, was the last thing she wanted to do.
But the tired body and emotionally exhausted mind overpowered her alertness at some point in the night. And the silence between the two of them acted like a sweet lullaby.
Darius deliberately did not strike any conversation as he knew it would keep her engaged, and she would not sleep then.
He lay on the rocks some feet from her, staring at the starry sky.
She must be wondering why he did not fall asleep. He couldn't! He was a Vampire after all. The only reason he slept was the Vampires had accustomed to the habits of humans.