Why do we get headaches?

The brain itself cannot feel pain because it lacks pain receptors, so headaches actually come from the tissues surrounding it: blood vessels, the membranes covering the brain, and the muscles and nerves of the head, scalp, and neck. Tension headaches, the most common type, are linked to tightened muscles and stress. Migraines involve waves of abnormal nerve activity and changes in blood vessels, often producing throbbing pain, nausea, and sensitivity to light. Other triggers include dehydration, lack of sleep, eyestrain, caffeine withdrawal, hunger, and certain foods. Cluster headaches are rarer but extremely severe. Most headaches are harmless and pass with rest, hydration, or over-the-counter pain relief, though sudden severe headaches can signal a medical emergency.