Francis and the others had gotten used to staying in that dungeon, so they could come with precision how much time had passed since they entered. According to them, two days had passed. So, Billy decided to let everyone take a short nap. Sleeping inside the dungeon was too uncomfortable, so it wouldn't help much, but a short and deep nap probably could. In any case, Billy only checked his stuff since he was too used to his soft bed and while he occasionally could take naps inside the dungeon, it was hard to do so when he was the only one truly alert.