Captains have to sleep, which is why warships have a watch team who are awake. They failed here, which is unfathomable, but that is not, per se, the CO's fault. The CO has to sleep sometime -- I've stood many watches as the senior-most officer awake on a nuclear submarine while my CO slept, and I had to avoid collisions just as much as I would have had to do if my CO had been awake.

It is true that many COs will try to time their periods of sleep for when the operational tempo is lower as a risk management measure. I can only assume the Fitzgerald's CO had made his risk assessment and figured that it was better to sleep at night than to sleep during the day when the contact density would be even higher.

But for a Navy warship being "approached by other ships" is a fact of life for every hour of every day, you can't always plan your sleep schedule for when you're the only boat on the pond.

Other traffic is no reason to wake the captain, but when you're closing from 4000 yards to 3000 to 2000, well, you might want to give them a poke.

Yes, and every Captain out there puts the minimum "closest point of approach" for any contact that they're willing to accept into their standing orders, precisely so that they will be woken up by the watch team with enough time to make it to the bridge and assess the situation.

But this still relies on the watch team detecting the contact and realizing that it will pass near to the ship, and so again the ship's captain is back to relying on his or her watch team to at least get to that minimal level of competence -- because if they can't rely on the officers on watch to be able to wake them up properly, we're back to captains who can never sleep.