Why do dogs curl up while sleeping

When dogs sleep outside, in the wild, especially in colder areas, they will dig a shallower hole in the ground and curl up in it.
This provides them with warmth, and when we curl up in this way, the body maintains its temperature more easily. Also, in that position, the most sensitive internal organs are protected from the sudden attack of predators.
Dogs sleep in this position and in the house, in a safe place, although they are not in any danger. It sounds ridiculous, but it is a reasonable tactic inherited from distant ancestors.