About 39 million Americans live with migraine, yet most of them are still hunting for the one food, one smell, or one stressful day that “caused” their last attack. I spent two years doing exactly that before a neurologist explained something that made the whole puzzle click: migraine causes are almost never a single culprit. It’s a threshold problem, and once you get that, you start managing things very differently.
Let me walk through this with a real example. Sarah, a teacher in her late thirties, kept a trigger diary for months and blamed red wine after a bad attack on a Friday night. But she’d drunk the same wine the previous Friday with zero trouble. The difference wasn’t the wine. It was everything else that week, stacked on top of it.
That pattern is so common it almost defines the condition. Understanding the underlying biology is the only way to make sense of it.
What Actually Starts a Migraine
Migraine causes begin deep in the brain, not in the trigeminal nerve endings where the pain eventually lands. The process most researchers point to is cortical spreading depression, a wave of electrical and chemical disruption that rolls across the cortex at about 3 to 5 millimeters per minute. That’s slow enough to explain why aura symptoms drift across your visual field over twenty minutes rather than appearing all at once.
Once that wave passes, it triggers the release of a protein called CGRP (calcitonin gene-related peptide). Researchers pinned CGRP as a key pain messenger back in the 1990s, and it’s now the target of several newer preventive drugs. The trigeminal nerve dumps CGRP into the meninges, blood vessels dilate, inflammation builds, and you get the throbbing pain most people recognize.
What sets off that initial wave varies wildly between people, which is why “migraine causes” is such a loaded phrase. Rarely one thing.
The Threshold Model Explained
Think of your migraine threshold as a bucket. Everyone’s bucket is a different size, partly inherited, and various inputs drip into it all day: poor sleep, hormonal shifts, skipped meals, a low-pressure weather system moving through. When the bucket overflows, you get an attack.
Sarah’s Friday wine was just the last drop. Her bucket that week was already nearly full from end-of-term stress, two nights of broken sleep, and a barometric pressure drop that came through on Wednesday. Weather changes account for around half of reported environmental triggers in most survey data, which tells you how much is happening outside your control.
The threshold model also explains something that confuses a lot of people: the same trigger works differently on different days. That’s not random. Once I understood this, I stopped blaming specific foods and started looking at the whole week instead.
Hormones, Sleep and Diet Triggers
Estrogen fluctuation triggers attacks in a large proportion of female migraineurs, which is why menstrual migraine is its own recognized subtype. The drop in estrogen in the days before a period is particularly reliable as a trigger, and it’s one reason migraine is roughly three times more common in women than men after puberty. Hormonal contraceptives help some people and make things worse for others, so it genuinely depends on the individual.
Sleep cuts both ways. Disrupted sleep is a well-documented trigger, but migraine attacks also fragment sleep, so you can end up in a loop that’s hard to break. Oversleeping is just as much a trigger as undersleeping for many people, which feels genuinely unfair on a Saturday morning.
On the diet side, caffeine withdrawal is probably the most underestimated driver of migraine causes. Miss your usual morning coffee by a couple of hours and a rebound headache can start within 12 to 24 hours, because blood vessels dilate once caffeine’s constricting effect wears off. Alcohol, aged cheeses, and processed meats get blamed constantly, but the evidence that they cause attacks directly is weaker than most people assume. They’re more likely contributors when the bucket is already half full.
Managing Your Personal Trigger Load
The migraine causes that matter most are the ones you can actually move. Weather you can’t control, and genetics you can’t change. But sleep schedule, hydration, meal timing, and caffeine habits are genuinely modifiable, and they shift your baseline threshold more than any single dietary tweak.
What worked for Sarah was less about elimination and more about raising her floor. She standardized her sleep window to within 30 minutes every night, including weekends, and kept caffeine to one consistent cup at the same time each morning. She also started tracking barometric pressure on her phone so she could be more careful about sleep and alcohol on low-pressure days. Her attack frequency dropped from roughly three a month to one, without cutting out wine entirely.
A headache diary is still the most useful tool I’ve come across, but track your whole bucket, not just what you ate. Note sleep hours, stress level out of ten, cycle day if relevant, and weather. After six to eight weeks, patterns usually emerge that a food diary alone would never show you. If attacks are frequent or severe, a neurologist can also discuss CGRP-targeted preventives, which have changed the treatment picture considerably since their approval around 2018.
FAQs
What is the most common cause of migraines?
There’s no single most common cause. Stress, hormonal shifts, and sleep disruption are the most frequently reported contributors, but attacks almost always result from several factors reaching a threshold together.
Can dehydration alone cause a migraine?
It can tip someone over threshold, especially if other factors are already elevated. But dehydration alone rarely causes a full attack in someone with a naturally high migraine threshold.
Why do migraines run in families?
Genetic variants affect how excitable your brain’s neurons are and how large your threshold bucket is. If a parent has migraine, your lifetime risk is roughly double that of someone with no family history.