Self-conscious urticaria is especially obvious at night, which may be related to the following aspects:1, the vagus nerve is more excited at night, resulting in greater mast cell sensitivity, mast cells release inflammatory mediators caused by vasodilation, vascular permeability increases thus aggravating urticaria.2, the night human body is in the state of impending sleep, there is not much to distract attention, the slight itching symptom will be enlarged, scratching leads to artificial Urticaria, thus aggravating the symptoms of urticaria. 3, the body is in the bed sheet, quilt package at night when you sleep, and the bed sheet, quilt cover, pillow contains a large number of dust mites, dust mites are one of the common allergens, the body receives contact with the allergens, will produce antigen antibody reaction leading to urticaria aggravation. 4, if there are pets, such as cats, dogs and other types of pets, like to curl up in the bed and the body’s Dog hair, cat hair is also a common allergen, easy to induce allergic reactions.