Pain in the buttocks when lying down is mostly likely to be caused by the following reasons: First, the patient lies flat for a long time in daily life, and the blood vessels in the buttocks are compressed, resulting in poor blood circulation and inducing the appearance of pain. Patients in this situation can properly exercise and massage the buttocks, which can well promote blood circulation and relieve buttock pain. Secondly, if the patient has hip pain on a regular basis, it may also be due to a lumbar disc herniation that compresses the sciatic nerve and the pear-shaped muscle syndrome that induces pain in the hip. If it is due to this cause, the patient should go to the hospital in time to check the severity of the condition and choose the appropriate treatment measures for treatment.