Re: Sleeping underway risk
Your question emphasizes the need for an awake and alert lookout on watch while underway. This is difficult to achieve when singlehanding on an extended voyage or a couple cruising together.
The potential risks of striking objects underway include floating but submerged trees and shipping containers. These are difficult or impossible to see at night and don't appear on radar.
In blue water, you can't anchor for the night somewhere protected. in inland and coastal waters, you usually can!