Unless your head is made of fairy floss or you're very, very lucky, chances are you know what it's like to be struck down with a killer headache.
And while there are many proposed reasons as to why headaches occur -- eyesight problems, muscular tension or dehydration are all worthy examples -- the common headache is actually far more mysterious than it might first appear.
"The headache in general is a mystery," Professor Paul Rolan of the University of Adelaide told The Huffington Post Australia.
"Because the normal function of pain is to alert you to something dangerous in your body. So if you have a broken leg or a wound, you are going to feel pain in order to alert you to that. Pain is an intrinsic defence mechanism. It’s attention grabbing, you can’t ignore it.
"Most pain is because there is a problem. If you have acute chest pain, it might be due to heart disease, for instance. Or tummy pain could be due to bowel problems.
"When it comes to problems with the head, there are of course people who have found their head pain was due to something underlying, but I could probably count them on the fingers of my hands.
"For the most part, it's a bit of a mystery. There is no benefit to getting a migraine. So what's wrong with us? Why do we keep getting pain in something, only to find nothing is wrong with it?"
Rolan thinks the reason we get headaches might have something to do with the critical importance of our brain and its function... in other words, it's just too important to risk.
"My guess is it has something to do with the development of the human brain. I believe we are actually wired to pay extra attention to that part of the body because it's so important," Rolan said.
Of course, Rolan doesn't know for sure, and that's partly due to the fact the living brain is notoriously difficult to study.
"Almost all the other headache conditions, it's a case of 'GOKAHWT' -- God Only Knows And He Won't Tell," Rolan said.
"But seriously, how do you study it? How do you study, for instance, an ice cream brain freeze? It really is quite hard to study the living human brain. Of course there are certain things we can do, but really, the cause of almost all headaches is actually unknown."
Rolan points out this isn't necessarily the case when it comes to treatment of headaches (though he says most of these are discovered by trial and error) but more in terms of why the headache is happening.
"What we are not very good at is working out why some things hurt," Rolan said. "It's very hard to do those experiments.
"We are far better at working out treatment, though most of it's discovered by trial and error. Seriously, most of the treatments we have -- I think there is only one class that was specifically and intentionally developed for the migraine. The rest have been initially for another condition.
"It's much like how Viagra was discovered. Initially it was being used for heart treatment, until patients came back and said, 'Doctor, I have had some very interesting side effects'. The discovery was totally by chance."
However, Rolan believes more answers to why certain things occur in the brain -- and the rest of the body -- will be available in the not-too-distant future, and patients shouldn't be shy away from being involved.
"It's coming along fairly quickly. Only recently there was a scanning trial published that examined a new way at looking at activity -- the tools are coming out there.
"I think it's also important that patients are active participants when it comes to their care. Modern medicine has come such a long way even in my lifetime -- I mean I'm old enough to remember when we still used to write in Latin. That was before I graduated, but still.
"Patients weren't meant to know what they had wrong with them. They were just the passive recipient of medical care.
"These days, modern doctors aren't threatened by a patient's opinion in terms of what could be going on. Most of us are very happy with patients trying to help and being actively being involved in their health care.
"I think patients being involved in their treatments is a good thing. Coupled with the way medicine is advancing, I think all of this is makes for a positive sign for the future."