While on the Argo II, after Coach Head left, the demigods would fall asleep anywhere and everywhere.
Most days, they'd be too exhausted to even make it back to their cabins before crashing. They'd fall asleep in the mess hall, at the helm, on deck, or in the middle of the hallway.
This was how they discovered that Jason drooled almost as much as Percy, Leo lit himself on fire in his sleep, and Hazel summoned countless gems.
On colder nights, they demigods would snuggle together for warmth. Frank ended up getting used as a pillow a lot, but he didn't seem to mind at all. Although he'd once turned into a snake in his sleep, which had sent a screaming Piper out of the room.