Whether it’s one of those low-key, long-lasting headaches or a soul-splitting migraine that literally hits you over the head, figuring out the cause is the key to relief.

A study published in Neurological Sciences found that almost half of its participants suffered from a headache up to 12 days out of the year. And nearly 35 percent suffered from one up to 52 days.

All in all, headaches affect up to 80 percent of the U.S. population, according to Otolaryngologic Clinics of North America. “At least one patient a day will come to me with headaches as a chief complaint,” says Svetlana Kogan, MD, a board-certified internal medicine doctor in New York, NY. “[But] having a headache more than several times a week is definitely a problem.”

So What Is A Headache, Really?

According to the Mayo Clinic, there are different kinds of headaches. A primary headache is caused by over-activity of or problems with pain-sensitive structures in your head—like chemical activity, the nerves or blood vessels surrounding your skull, or the muscles of your head and neck. 

Then there are secondary headaches, which come on as a symptom of another issue that activates pain-sensitive nerves in the head. Some examples may include acute sinusitis, ear infections, dehydration, or the flu.

Either way, if you’re suffering from headaches, getting to the root cause is key so you can work with your health care provider to pinpoint the best treatment plan. It’s also important to note that chronic headaches (headaches that occur 15 days or more a month, for at least three months, according to Mayo Clinic) might be the result of something more serious, like problems with blood vessels in and around the brain, or an infection like meningitis. If you’re dealing with headaches more days than not, especially if you’ve had cancer or are pregnant, definitely see your health care provider to rule out serious health concerns, Kogan advises.

Here are seven issues that could be at the crux of your suffering:

1. Hormones

Women sometimes have their reproductive cycles to blame for painful headaches. Hormonal shifts and headaches—usually migraines—go hand-in-hand. In fact, up to 70 percent of migraine sufferers report a connection between their periods and migraine attacks.

The Cleveland Clinic in Ohio notes that this may have to do with decreasing levels of estrogen before the start of menstrual flow. If you get headaches when you’re PMS-ing, it could be linked to estrogen and progesterone dropping to their lowest levels.   

2. Allergies

Hay fever (or, rhinitis) is so common that we often shrug it off as a normal side effect of living through spring or fall. But if your headache is in the front of your head and causing pain in one or more areas of your face, ears, or teeth, it could be tied to acute or chronic rhinosinusitis, an inflammation of the sinus resulting from allergies or even an infection.

3. Eyestrain

We spend so much time looking at digital devices that we often discount the effect all that staring into a bright screen has on our eyes. If you find yourself suffering from a headache after a long day in front of your computer without sufficient breaks or after spending a little too long messing around with your Snapchat filter, it may be due to eyestrain.

Recent research published in Clinical and Experimental Optometry concluded that just an hour (maybe as long as your train commute time) of reading from a smartphone intensifies eyestrain symptoms. Some evidence suggests that lutein can help fight against those screen-staring symptoms, but you should try to reduce looking at bright screens when you can.

Related: Shop headache products. 

4. Forgetting to eat

Whether you’re fasting for health or personal reasons or skipping a meal when you’re too stressed or busy, going too long without eating can cause your blood-glucose levels to drop, which can result in migraines or other headaches. Tip? Get a few healthy snacks in several times throughout your day.

5. Stress

Feeling stressed all the time is often linked to heightened sensitivity to pain. This type of chronic headache is often marked by a pain that’s dull, constricting, pressing, or tightening, and of mild to moderate intensity, says The Mayo Clinic. It can also be felt on both sides of your head. Tension or tension-type headaches (TTH) are very common, affecting up to 78 percent of headache patients in population-based studies, notes the Annals of Indian Academy of Neurology.

When your headaches are linked to stress, try meditation or even yogic breathing, says Kogan. “This Ayurvedic breathing technique is preventative for stress headaches, especially, if you do three to five breaths in the morning, three to five in the daytime, and again at night.”

6. Sitting too much

The fact that more and more of us are leading a sedentary lifestyle these days can lead to tension headaches. “We’re sitting, staring at the computer all day long, and then, we’re looking at our cell phones,” says Dr. Kogan. ”So, when you’re constantly sitting with your head at a certain angle—looking at the computer or cell phone—you’re definitely going to have muscle spasms and tension headaches as a result.”

Dr. Kogan recommends patients suffering from tension try a combo of stretching and supplements: “During the day, take breaks to get up, move around, and rotate your neck gently several times clockwise and several times counterclockwise, then move it from side to side.” She also advises talking to your healthcare provider about supplements like feverfew or magnesium oxide.

Related: 12 Natural Ways To Kick Your Stress To The Curb

7. Too much coffee, soda, or energy drink

If you’ve heard that drinking caffeine can actually help address a headache, you’re not alone. Headaches enlarge blood vessels, which makes caffeine (which causes blood vessels to narrow and restrict blood flow) a natural foe. So, a little bit of the stuff helps.

However, the National Headache Foundation warns that too much caffeine can trigger what’s called “caffeine rebound,” which occurs from the withdrawal of caffeine after a sufferer continually consumes too much of the substance. In fact, they advise that chronic headache sufferers avoid drinking caffeine on the regular.

Related: How I Kicked My Coffee Habit For Tea—And Lived Happily Ever After

8. Taking pain medication too often

Yep, the plan of attack for a headache could be causing more headaches! If you take over-the-counter (OTC) analgesics—such as acetaminophen, ibuprofen, aspirin, or a pain-relief medication containing caffeine—three or more days per week, you could experience medication-overuse headaches or rebound headaches.

The reason? Painkiller overuse appears to interfere with the brain centers that regulate the flow of pain messages to the nervous system, making headache pain worse, notes the Cleveland Clinic. In this case, your best bet is to work with a health care provider to break the cycle and zero in on the root of your headaches.