Tension and Neurological Causes

• The exact causes for headaches are unknown, though researchers have studied the possibility that they are caused by changes in chemicals in the brain. These chemicals, such as serotonin, endorphins and other chemicals, act as communicators for the body's nerve system, and when there is a fluctuation in these chemicals, the brain becomes more vulnerable to pain signals that it is unable to suppress. A more likely possibility for the occurrence of headaches are tension and muscle tensions. This occurs when the neck and scalp muscles contract or become more tense. Other causes for headaches can occur through stress, depression, anxiety, poor posture, jaw clenching, head injury and other repetitive bodily motions that cause muscle tensions.
  
  

Habits and Diets

• Certain foods and lifestyle habits have been known to also cause headaches. Caffeine is a major contributor for headaches in some people. A person is likely to trigger headaches when he drinks coffee excessively or suffers through withdrawals by stopping cold turkey. Chocolate, cheese, nuts and alcohol are also known causes for headaches. Heavy smokers also experience headaches.
  
  

Other Causes

• Headaches can also occur through a number of different but common causes. For instance, colds and flu, or symptoms of these illnesses, such as nasal congestion, can lead to headaches. Headaches are also common among those who strain their eyesight through activities such as prolonged staring at computer monitors or reading. Sinus infections, which is often the cause of allergies, and overexertion can bring on headaches as well.