Those who are prone to migraines know what it feels like to have one starting. It’s a special kind of headache that goes way beyond just pain and can include nausea, vomiting, painful sensitivity to stimuli, blurred vision, and even loss of consciousness. What we’re not sure about is why some people get migraines and why there are so many different triggers for them. Some people can have migraines that are triggered by anything from a change in the weather to bright sunlight and physical exertion. For some, it’s sensory—migraine can be triggered by a certain smell or exposure to a certain food, drink, or food additive.Even those sensitive to certain triggers don’t always get migraines when they’re exposed to those triggers, and they can also come down with a migraine without being exposed. Just why it happens to people isn’t known, although it’s suspected that there’s a genetic connection, because migraines seems to run in families. One suggestion is that people susceptible to migraines have parts of their brains that are more sensitive to certain stimuli than others or that migraines happen in response to certain changes in brain chemistry. So far, though, there have been no concrete findings regarding just what causes migraines in some people and not others.