The drowsiness at the back of the head may be related to autonomic dysfunction, or it may be caused by cervical spondylosis and insufficient blood supply to the cerebral arteries. 1. Autonomic Nerve Function Disorder: If long-term mental tension, psychological pressure, or excessive late-night sleep, resulting in poor sleep quality and insufficient sleep time, which in time will easily lead to autonomic nerve function disorders, it may show drowsiness in the back of the head, which may also be accompanied by headache, weakness and other symptoms. 2. Cervical spondylosis: If patients with this disease keep a fixed posture for a long time, it will easily lead to tension and stiffness of the neck muscles, which may show drowsiness in the back of the head, accompanied by neck and shoulder pain, stiffness, numbness of the upper limbs and other symptoms. 3. Insufficient blood supply of cerebral arteries: usually due to atherosclerosis, resulting in blood circulation obstacles in cerebral arteries, resulting in insufficient blood supply and oxygenation of local brain tissues, which may cause drowsiness in the back of the head, and may be accompanied by headache, dizziness and other symptoms. Dullness in the back of the head may also be caused by other reasons, if the symptoms continue to be unable to relieve, or there are other obvious discomfort, you should consult a doctor as soon as possible to diagnose the cause of the problem, and then give targeted treatment.