A headache is pain or discomfort in the head, scalp, or neck. Serious causes of headaches are extremely rare. Most people with headaches can feel much better by making lifestyle changes, learning ways to relax, and occasionally by taking medications. The most common headaches are probably caused by tight, contracted muscles in your shoulders, neck, scalp, and jaw. These are called tension headaches. They are often related to stress, depression, or anxiety. Overworking, not getting enough sleep, missing meals, and using alcohol or street drugs can make you more susceptible to them. Headaches can be triggered by chocolate, cheese, and monosodium glutamate (MSG). People who drink caffeine can have headaches when they don't get their usual daily amount.