Waking up with a soybean-sized pimple at the root of the back of the ear is mainly considered to be related to enlarged lymph nodes, folliculitis, and sebaceous cysts. 1. Enlarged lymph nodes: common lymphadenitis, which can lead to enlarged lymph nodes, appearing behind the root of the ear a soybean-sized lump. 2. Folliculitis: Inflammation of the hair follicles behind the ear can lead to the appearance of soybean-sized bumps on the affected area, accompanied by heat, redness, swelling, distension and other uncomfortable symptoms. 3. Sebaceous cysts: The sebaceous ducts in the skin behind the ears are blocked, and sebum is trapped to form cysts, which are slow-growing and basically have no other symptoms. When this symptom occurs, it is recommended to consult the hospital, after the diagnosis is clear, follow the doctor’s instructions for treatment.