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Why Migraines Happen: The Complete Guide

woman with migraine attack

You know the feeling: your head starts throbbing in the middle of a busy day, and soon even the faintest light is unbearable. Today, migraine is the third most prevalent illness in the world, affecting about 1 billion people worldwide—many of whom experience 15 or more attacks per month.

While research has evolved, doctors still don’t know the exact cause of migraine headaches, which can lead to additional frustration for those who suffer. Here we’ll explore what the latest research shows about why migraines happen - from chemical compounds and hormones to possible triggers, causes of migraine for males and for females, and common pre-migraine symptoms. Plus, find out why it can lead to fatigue, and the degree to which migraine is dangerous.

Why do migraines occur?

In most cases, migraine affects people whose brains are abnormally sensitive to even the smallest deviations from ideal conditions in the environment and the body. Although we don’t fully understand the causes of this abnormal brain sensitivity, we now believe that both migraine genes and environmental factors contribute greatly to the susceptibility to migraine. While most migraine attacks begin in the brain, the headache itself begins when nerves that sense what happens in the dura (inside the head) become active and send millions of pain signals to the brain.

What triggers a migraine headache?

Emotional and physiological internal states such as being happy or sad, stressed or relaxed, angry or loving, feeling lonely or being socially engaged, and being hungry, thirsty, tired or at the onset of menstrual cycle can all trigger a migraine. External conditions such as being exposed to bright or flickering light, loud noise, certain odors, changes in barometric pressure, uncomfortable heat or cold, demanding physical effort, travel-related time-zone changes and insufficient sleep can also trigger a migraine.

Below is a list of factors that many people with migraine believe trigger their attacks. Studies on migraine triggers revealed that none of these triggers is reliable and that in reality, a migraineur can be exposed to many of the common triggers listed below without experiencing migraine. While some sufferers find this list helpful, we must remember that the chances of getting a migraine when exposed to these triggers is actually very low.

1. Stress

According to the Anxiety and Depression Association of America, “40% of adults experience persistent stress or excessive anxiety in their daily lives.”

2. Hormonal shifts

Estrogen controls chemicals in the brain that affect the sensation of pain. The menstrual cycle, pregnancy, perimenopause and menopause, and birth control pills can cause estrogen to rise and fall. And furthermore, Healthline says that “a drop in estrogen levels can potentially trigger a headache.”

3. Smells such as perfumes

Chemical exposure or scents from certain products such as air fresheners, cleaners, deodorants and perfumes may play a role in headaches. One study reported that “of the general population surveyed in America, 98.3% are exposed to fragranced products at least once a week... Overall, 34.7% reported one or more types of adverse health effects from exposure to one or more types of fragranced products, with 15.7% suffering from migraine headaches.”

4. Smoking or being around smoking

Both smoking and inhaling secondhand smoke can trigger a headache. Because nicotine is a vasoactive substance, it “changes the size of blood vessels in the brain, and that can cause headache.”

5. Exercise or physical stress

Rotating your body quickly, turning your head suddenly, or bending over can all trigger or aggravate migraine symptoms. While exercise often helps manage the symptoms of migraine, exercise-induced migraines can be triggered when engaging in vigorous sports such as weightlifting, rowing and even running.

6. Changes in sleep patterns

Too much sleep, too little sleep, changes in when you sleep, poor quality sleep, and even sleep apnea could all have an impact, because sleep, headache and mood all share common neurotransmitters. A study of 1,283 migraine patients found that over half had reported difficulty getting to sleep and staying asleep at least occasionally.

7. Dehydration

Not drinking enough water can impact migraines. Not consuming enough liquids causes blood volume to drop, decreasing blood flow to the brain; the loss of electrolytes might also be a culprit.

8. Flickering lights

Different types of light, including “flickering or pulsing lights, repetitive patterns, glare, bright lights, computer screens, TV, and movies,” can trigger migraine attacks. Fluorescent light’s invisible pulsing could be particularly instigative to those with photophobia.

9. Weather changes

According to the UK’s National Health Service, “grey skies, high humidity, rising temperatures and storms” can lead to migraine attacks. This is because even tiny decreases in barometric pressure can trigger a migraine, and that can happen especially rapidly during hurricanes and other large storms.

10. Alcoholic beverages

Of course red wine is a well-known migraine trigger, but all alcoholic drinks dilate blood vessels in the brain, which can lead to migraine attacks.

11. Certain foods

Chocolate is a common trigger, as it affects an estimated 22% of migraineurs. Lunch meats high in nitrates can release nitric oxide into the blood, which is thought to dilate blood vessels in the brain and can cause or contribute to migraines. Onions and aged cheeses have higher tyramine content, which is linked to migraines, and certain fresh fruits such as bananas and citrus fruits may also be triggers.

What causes migraines in females?

Migraine is one of the leading serious health problems affecting women, impacting 18% of all women in the US. Of the more than 39 million American sufferers, 28 million are women.

Migraine in women is often associated with fluctuating hormone levels, which may help explain why they are more likely to suffer from migraine attacks than men. Women’s estrogen levels vary throughout their lives, with increases during fertile years and decreases afterwards. In fact, WebMD reports that "many women find their migraines improve or disappear after age 50."

What causes migraines in males?

While migraine tends to be more prevalent in women, it also affects an estimated 6-9% of men, many of whom inherit the condition from their parents. Additionally, headaches that resemble migraine are also common among athletes and military personnel following their exposure to repeated head traumas with and without loss of consciousness. These migraine-like headaches are called post-traumatic headache.

Athletes with concussions sustained during contact sports show greater incidence of migraine symptoms. In fact, a 2005 study found that concussed athletes demonstrated significantly greater migraine symptoms. This risk tends to disproportionately affect men, as shown in a 2014 survey of 37 countries that found men across the globe were more likely to play competitive sports than women.

Also, research has shown that men in the military are disproportionately likely to suffer from migraines due to PTSD. In one study, out of 2,200 returning male soldiers, 19 percent suffered from migraines.

Now that we’ve explored some potential underlying causes, we’ll examine pre-migraine symptoms that typically warn migraineurs of an oncoming attack.

Pre-migraine symptoms

Pre-migraine symptoms can vary based on the type of migraine. The two most common types of migraine are classified based on symptoms that signal when an attack is about to begin: migraine with aura or a "classic" migraine, and migraine without aura, also known as a "common" migraine.

A few hours before a migraine attack, you might experience subtle changes including:

  • Irritability
  • Nausea
  • Constipation
  • Mood changes, from depression to euphoria
  • Food cravings
  • Neck stiffness
  • Increased thirst and urination
  • Frequent yawning
  • Anxiety
  • Depression
  • Exhaustion

What is migraine aura

An aura can involve seeing a sparkling or flashing line or blind spots. And it is sometimes paired with tingling or numbness on one side of the body such as in the hand, arm, leg, or face. It can come on quite suddenly and according to the Mayo Clinic, “migraine aura usually occurs within an hour before head pain begins, and generally lasts less than 60 minutes.”

Different sufferers experience many variations of visual aura, including:

  • Flashes of light
  • Blind spots (scotomas)
  • Shimmering stars
  • Blurry vision
  • Losses in vision
  • Wavy or jagged lines

Now that you know the causes and pre-symptoms, let’s explore the symptoms of a migraine attack.

What are symptoms of a migraine attack?

Migraine has extremely incapacitating neurological symptoms, and usually lasts from four hours to three days. During a migraine, you’ll likely experience moderate to severe pain in your head that may radiate toward your eyes, forehead, or temple. It can happen on just one side of your head, but in about 1/3 of attacks, both sides are affected. And the pain can throb or pulse.

This pain can also cause nausea, vomiting, or vision problems. And you could experience dizziness, disorientation, or feeling faint. You may also have muscle tenderness and pain from light touch. And as a result, basic physical activity can be hard to tolerate.

Sensitivity to light, sound, and smell are also quite common. Studies by Harvard's Dr. Rami Burstein show that everyday light - made up of red, yellow, green, and blue - generates large electrical signals in the eye and brain, which tend to hurt people with light sensitivity (however, a very specific narrow band of green light generates smaller electrical signals in the eye and brain, minimizing irritation).

The International Headache Society recommends diagnostic criteria for migraine that include at least five attacks with:

  • Headache attacks lasting 4-72 hr (untreated or unsuccessfully treated)
  • Headache has at least two of the following four characteristics:
    • unilateral location
    • pulsating quality
    • moderate or severe pain intensity
    • aggravation by or causing avoidance of routine physical activity (eg, walking or climbing stairs)
  • During headache at least one of the following:
    • nausea and/or vomiting
    • photophobia and phonophobia
  • Not better accounted for by another ICHD-3 diagnosis.

Now that you know the common symptoms of migraine attacks, let’s dig into why they can make you feel so fatigued.

Why do migraine attacks make you tired?

In the 2018 Migraine In America survey, 79% of respondents listed fatigue as a top migraine symptom - just below head pain, sensitivity to light, difficulty concentrating, sensitivity to sound, and brain fog.

Migraine affects a part of your brain (called the hypothalamus) that controls your energy, metabolism, heart rate, blood pressure, breathing rate, and your sleep and wake periods. The prolonged disruption of normal functioning of this brain area makes you feel tired, exhausted and fatigued. But fatigue is not the only impact.

Are migraines dangerous?

While pain, light sensitivity and other symptoms can severely impact sufferers’ quality of life, historically migraine has not been considered to be otherwise dangerous. However, a number of more recent case-control and cohort studies indicate that “migraineurs, particularly those with aura, have a higher risk of ischemic (but not hemorrhagic) stroke.” Fortunately, the incidence of such events remains very low.

Now you know more about why migraines happen

While much about migraines is still a mystery, your migraines don’t have to win. Now that you know more about what can potentially cause migraine attacks for males and for females, you can be on the lookout for pre-migraine symptoms. And, you can be confident knowing you are not alone. The research continues. Up next, learn all about green light therapy.