Itchy back at night, nothing during the day may be allergic dermatosis, scabies and other causes. 1. Allergic skin disease: allergy-prone people, when the back comes into contact with certain allergens, such as clothing, massage milk, bed sheets, etc. may induce allergic skin disease, or when sleeping at night when the temperature changes, may make the itching symptoms worse, appearing at night itchy back, daytime all right phenomenon. 2. Scabies: when the scabies mite parasites in the epidermis of the human back skin, there will be scabies mite infection, manifested as pimples, blisters, and scabies crawling on the surface of the skin digging tunnels, accompanied by intense itching, due to the scabies mite more frequent activities at night, the infection can appear at night back itching, daytime is fine symptoms. Itchy back at night, nothing during the day may also have other causes, it is recommended to go to the hospital in a timely manner to improve the examination, to clarify the cause of the disease to give targeted treatment.