My six-year-old usually wakes up with blood running from his nose. what is causing this?

Epistaxis: Nose bleeds are common in children with allergies or on antihistamines for allergies. The inflammation from this hypersensitivity is often worse with dry air, nose picking, blowing, etc. In the absence of any other abnormal bleeding (little red dots to the skin, bleeding from the gums, rectum, etc.) humidification of the bedroom with or without prescribed nasal steroid sprays is helpful.