It seems to me that nobody who has a goal can expect to sleep easily at night, at least nobody who can be reasonably expected to achieve that goal. Nor do people in authority sleep undisturbed at night, not if they accept responsibility as the price of their authority.
What Keeps Them Up At Night
No, the question which the answer to best defines them is not whether something keeps them up at night. It is what exactly does so. Just as a person’s strength can be gauged by the quality of their enemies, a person’s character and worth may be judged by their worries and fears.