Your migraine is the result of abnormal electrical and chemical activity in your brain, not just a bad headache. While tension headaches involve muscle tightness, migraines involve waves of nerve cell activation that spread across the brain’s surface, triggering inflammation and pain signaling. The specific reason yours showed up today depends on a combination of your genetics, your environment, and what your body has been through in the past 24 to 48 hours.
What’s Happening Inside Your Brain
A migraine starts when neurons and surrounding cells in the brain’s outer layer fire in a spreading wave of hyperactivity, followed by a wave of suppression. This phenomenon, called cortical spreading depression, moves across the cortex and is especially active in areas that process vision, which is why many people see flashing lights, zigzag lines, or blind spots before or during an attack.
That wave of electrical activity releases a flood of inflammatory molecules, including potassium ions, nitric oxide, and prostaglandins. These chemicals activate branches of the trigeminal nerve, the major pain pathway for the head and face. Once the trigeminal system fires, it sends pain signals that produce the throbbing, often one-sided headache most people associate with migraines. The blood vessels around the brain become inflamed and sensitized, which is why even your pulse can feel like it’s pounding in your skull.
A brain region called the hypothalamus also plays a central role. It regulates your sleep-wake cycle and keeps your internal systems stable. Researchers believe it contains a kind of “trigger switch” that, when disrupted, can initiate the cascade of events leading to a migraine. This is why changes in sleep, stress, or routine so reliably set off attacks.
The Most Common Triggers
Migraines rarely have a single cause. They’re usually the result of several factors stacking up until your brain hits a threshold. Understanding your personal triggers can help you identify patterns over time.
Sleep disruption. Both too little and too much sleep can provoke a migraine. People with migraines are significantly more likely to experience poor sleep quality, insomnia, and nighttime fatigue. A late night, a shift change, or even sleeping in on weekends can be enough to destabilize the hypothalamus and set off an attack.
Stress and the letdown effect. Stress itself is a trigger, but so is the sudden drop in stress. Many people get migraines on the first day of a vacation or the morning after a high-pressure deadline. The shift in cortisol and adrenaline levels appears to lower the brain’s threshold for that spreading wave of nerve activation.
Hormonal changes. Drops in estrogen are one of the most potent migraine triggers. Many people report migraines in the day or two before their period starts, when estrogen falls sharply. Steady estrogen levels tend to improve headaches, while any significant fluctuation, including those during perimenopause or after stopping hormonal birth control, can make them worse. This hormonal connection is a major reason migraines disproportionately affect women.
Food and drink. Certain compounds in food can provoke attacks in susceptible people. The most commonly implicated are tyramine (found in aged cheeses, cured meats, and fermented foods), sulfites (in wine and dried fruits), MSG (in many processed and restaurant foods), and aspartame (in diet sodas and sugar-free products). Skipping meals or becoming dehydrated are equally reliable triggers, sometimes more so than any specific food.
Environmental changes. Shifts in barometric pressure, bright or flickering lights, strong smells, and heat are all recognized triggers. Many people notice that migraines cluster around weather fronts or seasonal transitions.
Genetics Set the Stage
If one or both of your parents get migraines, your risk is substantially higher. Heritability studies estimate that genetics account for about 48% of migraine risk in women and 38% in men. Familial factors contribute to roughly half of all migraine cases, meaning the other half comes from environment and lifestyle.
What’s inherited isn’t a single “migraine gene” but a collection of variations that affect how your brain handles electrical signaling, inflammation, and chemical balance. Some of the best-understood mutations involve genes controlling calcium channels and sodium-potassium pumps in nerve cells. These channels regulate how easily neurons fire, and variants that make them more excitable lower the threshold for that spreading wave of brain activity. You don’t need to know your specific genetic profile to manage migraines, but understanding that your brain is wired with a lower activation threshold helps explain why triggers that wouldn’t bother someone else can set off an attack in you.
The Four Phases of a Migraine
A migraine is not just a headache. It unfolds in up to four distinct phases, though not everyone experiences all of them.
Prodrome begins hours or even a day before pain starts. You might notice food cravings, mood changes, neck stiffness, frequent yawning, or unusual fatigue. These early warning signs originate in the hypothalamus and brainstem as the attack builds.
Aura affects roughly a quarter of migraine sufferers and typically lasts 20 to 60 minutes. Visual disturbances are the most common: shimmering arcs, blind spots, or patterns that slowly expand across your field of vision. Some people experience tingling in the face or hands, difficulty finding words, or even temporary weakness on one side of the body. Aura corresponds directly to that wave of electrical activity sweeping across the cortex.
Headache is the phase most people recognize. The pain is often pulsating, frequently one-sided, and typically worsens with physical activity. Nausea, vomiting, and extreme sensitivity to light and sound are hallmarks. This phase can last anywhere from 4 to 72 hours.
Postdrome, sometimes called a “migraine hangover,” starts as soon as the pain resolves and can linger for hours to two full days. Symptoms include fatigue, body aches (especially a stiff neck), difficulty concentrating, dizziness, lingering light and sound sensitivity, and mood shifts ranging from euphoria to depression. Many people describe feeling “washed out” during this phase.
Why Women Are Hit Harder
Globally, about 2.9 billion people experienced headache disorders in 2023, and migraine accounts for a significant share of that burden. The disability caused by headache disorders is more than twice as high in women compared to men. Women not only have higher migraine prevalence but also spend a greater proportion of their time in active headache episodes.
The estrogen connection explains much of this gap. The hormonal fluctuations of menstruation, pregnancy, postpartum recovery, and menopause create recurring windows of vulnerability. Before puberty, boys and girls get migraines at roughly equal rates. After puberty, the ratio shifts dramatically, and it stays skewed until after menopause, when the gap narrows again.
Identifying Your Personal Pattern
Because migraines result from a threshold being crossed rather than a single cause, tracking your attacks is one of the most useful things you can do. A simple log that records your sleep, meals, stress level, menstrual cycle (if applicable), weather conditions, and any unusual exposures in the 24 hours before an attack will start revealing patterns within a few months.
Many people discover that their migraines require a combination of triggers. One glass of wine on a well-rested evening might be fine, but that same glass after a stressful day on four hours of sleep could guarantee an attack. This “stacking” effect is why migraines can seem random at first. They’re not random. Your brain has a threshold, and multiple smaller provocations can push you past it just as effectively as a single large one. Once you understand which factors stack up for you, you gain real leverage over how often your migraines occur.