Where do headaches come from?

Different types. There are several different types of headaches and each has it's own distinct characteristic.
Anything. Headaches can come from tension, dehydration, lack of sleep/poor sleep, skipping meals, stress, sleep apnea/snoring, or chronic sinus problems, teeth grinding, migraines.

Related Questions

Need doctor advice. Where do these frequent headaches come from?

Neurology Evaluation. In the general population, headaches are common. The nature and quality of the headaches is important in helping the neurologist figure out the etiology. If the headaches are new, a structural cause needs to be ruled out. Such entities as subdural hematoma/fluid collections, hydrocephalus, or brain tumors might be treated neurosurgically. See consultation with a neurologist. Read more...