cThankfully, the NHS says that most headaches are benign. The common condition can be triggered by things like dehydration, poor posture, drinking booze, not eating enough, and staying up too late. However, according to surgeon Dr Reza T, not all headaches are created equal. Cluster headaches, tension headaches, and migraines are the three main groups, he says. A fourth type, sinus headache, may reveal you’ve got a cold ― and there are signs in all headaches that prove you need to see a GP.How can I tell the four groups apart?Tension headaches are the most common form of headache, Dr Reza T says.Health information site