When your headache is so bad you have to take to your bed, turn out the lights, and shut yourself away from the world, that's a sign this is no ordinary headache - it's a migraine.
Thankfully, there is plenty you can do to tackle the pain.
For many, a migraine attack begins with pain on one side of the head. Occasionally, it spreads to the top, front and the opposite side. It is often a throbbing, pulsating ache. Many people feel extremely nauseous. About a quarter of sufferers will experience a preceding 'aura', a neurological sign of an imminent attack. Typical auras can include loss or blurring of vision, flashes of light, numbness in the limbs, problems with speech and other unusual sensory experiences.
Whatever form it takes, a migraine is a debilitating condition affecting mainly women (one in seven), although many more may experience an occasional attack.
Its causes are not entirely clear and are subject to debate, but the current thinking is that in certain individuals with a genetic disposition to migraines, internal or external triggers affect nerve centres in the brain. This causes an increase in electrical 'traffic' through the nerves leading to the forehead and temples. The blood vessels around the nerves become dilated, and that interaction causes the pain.
The frequency and duration varies, but the average sufferer will experience one attack a month, lasting between four hours and three days. Symptoms may be so severe that sufferers cannot function - many use strong painkillers or other medications, and can only cope by lying still in a quiet, dark room.