While tension headaches are the most frequently occurring type of headache, their cause is not known. The most likely cause is contraction of the muscles that cover the skull. When the muscles covering the skull are stressed, they may spasm and cause pain. Common sites include the base of the skull where the trapezius muscles of the neck inserts, the temple where muscles that assist the jaw to move are located, and the forehead.
There is little research to confirm the exact cause of tension headaches. Tension headaches occur because of physical or emotional stress placed on the body. Physical stress that may cause tension headaches include difficult and prolonged manual labor, or sitting at a desk or computer for long periods of time Emotional stress may also cause tension headaches by causing the muscles surrounding the skull to contract.