About 4 percent to 5 percent of U.S. adults suffer from chronic headaches, which may occur nearly every day, according to the Mayo Clinic. While an occasional headache is something that most people experience, frequent headaches can be a warning sign that something is amiss in your body.

If you get frequent headaches, it’s likely to be a tension-type headache. They account for 75-90 percent of frequent headaches.

The cause of the most commonly reported headache, tension headaches, is actually still unknown. An estimated 75 percent to 90 percent of people who complain of frequent headaches are suffering from tension headaches.

Some experts believe they stem from contracted muscles, while others believe they’re related to changes in your brain chemicals, such as serotonin, endorphins and others, which help your nerves communicate.

The good news is that these headaches are rarely the sign of something serious (see the end of the article for some rare, but serious, causes). Instead, tension-type headaches are related to lifestyle factors that you can influence.

Click here to find out the many triggers of tension headaches.