Well, I don't know. If he doesn't want to be disturbed by the breathing spectre, then he should respectfully say that he sleeps there now, and would they kindly leave him in peace.
My DD and family have recently moved into an 18th century house which is reputedly haunted. DGS 1 had been sleeping in his room for a few nights when his bed shook and he felt someone touch him. He thought it was his brother, but when he turned round nobody was there. My DD told him that if it happened again he should say something similar to the above.
Like your OH, my grandson was not in the least perturbed about it. They have lived in old properties as long as he can remember.