Why is diverticulosis only painful while laying down?

If you have: Known sigmoid diverticulosis coli and are having pain in left lower abdomen, it might mean you are developing acute diverticulitis. This requires antibiotics or sometimes even surgery. Get to a doctor for proper treatment.

Trick question?: Technically, diverticulosis as a condition shouldn't be painful at all. Diverticulitis can be painful, as it's an infection which would need to be treated. If you're having pains,,you should be evaluated soon.