So, he's not asleep, he's awake.  Admit him.
So?
His leg twitched. I don't see what! It's called a myoclonic jerk, it's very common when you're falling asleep. Respiration rate falls, and the brain interprets this as the body dying, so it sends a pulse to wake it up.
His leg twitched. I don't see what! It's called a myoclonic jerk, it's very common when you're falling asleep. Respiration rate falls, and the brain interprets this as the body dying, so it sends a pulse to wake it up. [SEP] So? [SEP] So, he's not asleep, he's awake.  Admit him.