According in my research the reasons why we get headaches are the following,
DEHYDRATION: This may be the most common cause of a headache. Your body is made up of roughly 60% water and requires a generous amount of water intake. Adults should be drinking about 8 to 10 glasses of water a day for proper hydration. Be aware that coffee and sodas are often dehydrating.PAIN MEDICATIONS: Ironic but true. Half of chronic migraines, and as many as 25 percent of all headaches, are actually "rebound" episodes triggered by the overuse of common pain medications.
CAFFEINE: Even though caffeine usually helps relieve headaches, too much of a good thing can actually have the opposite effect. Plus, there's the withdrawal factor. If you suddenly stop drinking coffee, you'll get a headache until your body adjusts to the loss of its daily fix.
STRESS: Tension headaches, the most common kind, are brought on by either physical or emotional stress. One of the most frequent causes of physical stress is spending too much uninterrupted time staring at the computer. Take breaks every half hour to stretch and look in the distance. Emotional stress may not be so easy to eliminate.
SINUSES: Dry sinuses or congested sinuses can cause headaches. These headaches come with deep and constant pain in the cheekbones, forehead or bridge of the nose. The pain usually intensifies with sudden head movement. Using a neti pot daily can help.
BLOOD SUGAR IMBALANCE: An imbalance in blood sugar (usually low) can be corrected by eating adequate protein. Protein helps to stabilize blood sugar levels.
CERTAIN FOODS: Peanuts, chocolate and red wine all contain a lot of the amino acid tyramine that can cause headaches. Other foods that contain nitrates can also trigger headaches including salami, hot dogs, and sausages. Although not as common, diary and wheat can trigger headaches, too.LACK OF SLEEP, SKIPPED MEALS, HANGOVERS.
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