In the vast majority of cases, the causes of headaches are not serious -- but sometimes a headache can signal a serious health problem like a brain tumour. Here are 5 red flags you need to know about. Modern life can be such a headache. In fact, headaches are so common that the World Health Organization says that in developed countries tension headaches affect two-thirds of men and over 80 per cent of women. And one in 20 adults experience a headache every day or nearly every day! Stress is a big culprit for our aching heads, but they can be caused by anything from a sinus infection and sleep disorder to dehydration, depression and the flu. And while in the vast majority of cases, the causes of headaches are not serious, a headache can also signal something far less benign ?like a brain tumour or another serious health problem. 밡inety-nine per cent of the time, a headache isn뭪 cancer,?Dr. Gene Barnett, director of the Brain Tumor and Neuro-Oncology Center at the Cleveland Clinic, told CNN. 밒t뭩 a stress headache or a migraine or sinusitis or something else benign.? Yet for some people a headache is the initial symptom of a brain tumour, experts say. So how to tell the difference between a typical headache and something more serious? Unfortunately, there뭩 no simple way to tell, and about half of the people with brain tumours don뭪 have headaches at all, according to Barnett. Still, there are some red flags that could signal that your headache is, in fact, a brain tumour. Headache or brain tumour? While these red flags could indicate atumour, it뭩 important to keep a few points in mind, experts say: first of all, your headache could fall into these categories and you could not have a tumour, and secondly, you could still have a tumour and not experience any of these symptoms. Symptoms are different for different people, and diagnosis usually involves several steps, including a neurological examination, brain scans and/or a biopsy. With that caveat, here are 5 red flags to watch for: Headaches are more severe in the morning. Experts say that when someone has a brain tumour, headaches typically begin in the morning, and at times, can be so severe that they wake you up. This kind of headache tends to ease up as the day goes on. By contrast, headaches that come on later in the day, and worsen into the evening, are often associated with the stresses and strains of everyday living. Headaches accompanied by other symptoms. Typical 멳rain tumour headaches?are usually accompanied by other symptoms such as vision problems, dizziness, nausea or vomiting (which is, again, usually most severe in the morning). Other warning signs are difficulty speaking, confusion, memory loss, or personality changes. Headaches can also be accompanied by more obvious symptoms of a serious problem such as weakness or paralysis in one part or side of the body and seizures or convulsions.