I've done and will shortly do a bunch of posts of articles on migraine triggers, but for Migraine & Headache Awareness Month I figured I'd throw a basic overview into a text post for those who are disinclined to read articles but could use the info.
Note before starting: the overall disease is called migraine; a specific episode of headache and other symptoms is a migraine attack. This is reflective of attempts to reframe migraine in order to communicate about it better. The thinking is that just like you would say "having an asthma attack" not "having an asthma," saying "having a migraine attack" reflects the nature of the disease better than "having a migraine." I will be using this terminology as much as possible.
Food triggers are far from universal and can be hard to pin down. Sometimes a food craving is part of migraine prodrome, so you eat the thing you're craving, the pain hits, and you assume that it was the food that triggered it when really the migraine attack had already started before you ate it. This is especially true for chocolate; contrary to popular belief, recent research says that it's not a migraine trigger for most people, and might even help relieve migraine attacks. Making it even harder to figure out what's what, the effects of a food trigger might not hit you until many hours, even a day later. If something jumps out at you as a definite trigger, obviously you should avoid it, but it's not worth making yourself nuts trying to tease out every food chemical that might sometimes trigger you. You can try an elimination diet like Heal Your Headache if you strongly suspect that you have food triggers and want to figure them out systematically, but don't feel like you're obligated to do that.
Other supposed sensory migraine triggers - bright or flashing lights, loud noises, strong smells, etc. - might also actually be exposure during migraine prodrome when your brain is already hypersensitive.
Changes and extremes of barometric pressure, temperature, and humidity can trigger attacks, as can lightning and other stormy weather. Some people find that WeatherX earplugs help prevent barometric pressure headaches, and in general it's probably worth keeping an eye on the forecast so you can adjust your plans or at least make sure to have relief meds on hand if it looks like it's going to be a triggering-weather day.
Migraine brains need consistency to stay calm. Both too little sleep (under 7 hours) and too much sleep (over 9 hours) can trigger an attack. Keeping your blood sugar fairly even is important; let it crash by skipping a meal, or eat a ton of sugar so it spikes and then crashes, and you're liable to get an attack. If your sleep cycle is all over the place or you eat at radically different times each day, you are setting yourself up for trouble. Also, for the love of all that's holy make sure that you stay well-hydrated; dehydration is a MAJOR migraine trigger. If you consume caffeine, make sure that you consume the same amount at the same time every day, and don't go above 200mg/day. If your caffeine consumption is irregular, you're liable to get a withdrawal headache that turns into a migraine attack, or conversely have your nervous system react badly to what it perceives as an overload. Both high stress levels and the physiological "let-down" of relieved stress can trigger attacks; stress management is important for migraine management. Hormone fluctuations can trigger especially nasty migraine attacks; ask your doctor about a migraine preventive and/or hormonal birth control if menstrual-related migraine is a problem for you. If your period is very regular, you might be able to do some form of "mini-prevention" regimen from a few days before to a few days after the expected beginning of your period, in addition to or instead of a continuous migraine preventive.
Migraine triggers are additive; usually it's not one specific thing that knocks you out, but a combo of them. The best analogy I've seen for this is a bucket of water that you put rocks in until it overflows. The water level is your migraine threshold, the overflow is an attack, and the rocks are potential triggers. Some triggers might affect you more strongly than others; think of them as different size rocks. You might be fine putting a medium-size trigger food rock into your bucket on a day when the weather's nice and you're well-rested, but if you put it in when your bucket already has the big rocks of bad weather and poor sleep sitting in it, your bucket will overflow. If you drop pebbles into your bucket all day, eventually it's going to overflow, even though no one pebble made much difference on its own.
It's always a good idea to keep a migraine diary to get a general overview of what possibly triggers and what best relieves attacks, (I use and highly recommend the free Migraine Buddy app for that,) but trying to figure out every single one of your personal triggers is likely to be more annoying than it's worth. Just maintaining a healthy lifestyle will probably go a long way toward preventing attacks.
Info summarized from a variety of content from Migraine Again, Association of Migraine Disorders, Migraine Buddy, Migraine.com, Migraine World Summit, and more
