"Nah," the Doctor said. "Not tired yet. But I won't go anywhere without you, you don't need to worry."

His voice was more flippant than he felt. He was so tired. So emotionally tired, but he couldn't make himself sleep. He thought, briefly, of the anesthetics in the infirmary, of forcing himself to collapse through that. But, really, he wouldn't really be resting, he'd just be unconscious.