Why Migraines Happen?

Migraine isn’t “just a bad headache.” It’s a complex neurological condition in which the brain temporarily functions differently from usual. During a migraine attack, the brain becomes unusually sensitive to light, sound, smell, movement, and even internal changes such as hormones or blood sugar levels. This heightened sensitivity explains why migraine is often accompanied by nausea, vomiting, visual disturbances, extreme fatigue, and difficulty concentrating.

At its core, migraine happens because the brain has a lower threshold for stress and change. When several triggers occur together, the migraine brain reacts strongly, setting off a chain of nerve signals, chemical releases, and inflammation that leads to pain.

Migraines commonly run in families. Research suggests that 60-70% of people with migraine have a family history, indicating a strong genetic influence. Certain genes affect how brain cells communicate, how easily nerves become overstimulated, and how pain signals are processed.

However, genetics alone does not cause migraine. These genes make the brain more sensitive, but environmental factors such as stress, poor sleep, dehydration, hormonal fluctuations, or skipped meals often activate this vulnerability. This is why migraine can appear at different stages of life and why people in the same family may experience very different symptoms.

Migraine develops in stages, showing that brain changes begin well before the headache.

Prodrome - This early phase can start hours or days before pain. Changes occur in brain regions that regulate sleep, mood, appetite, and energy. Common signs include fatigue, food cravings, irritability, neck stiffness, and mental fog. These symptoms are early warnings that the brain is under strain.

Aura - About one-third of people with migraine experience aura. Aura is caused by a temporary wave of altered electrical activity across the brain’s surface, briefly disrupting normal signalling. This can lead to flashing lights, zig-zag patterns, blind spots, or tingling sensations. Aura is reversible and neurological, not psychological.

Attack - This is the pain phase most people recognise. The headache is often throbbing, one-sided, and worsens with movement. Nausea, vomiting, and sensitivity to light and sound are common. During this stage, pain pathways in the brain are highly active.

Postdrome - After the pain fades, the brain needs time to recover. Many people feel drained, sore, emotionally low, or mentally slow. This “migraine hangover” reflects how much energy the brain used during the attack.

A migraine brain is naturally hyper-responsive. A key structure involved is the trigeminal nerve, which carries pain signals from the head and face to the brain. During migraine, this nerve becomes overactive and releases inflammatory chemicals around blood vessels, intensifying pain.

Another important factor is serotonin, a brain chemical involved in pain control, mood, sleep, and digestion. Fluctuations in serotonin during migraine disrupt normal pain regulation and blood vessel behaviour, helping explain why migraine is often linked with anxiety, sleep problems, and gut symptoms.

Migraines also involve disruption in the brain’s natural pain-regulating systems, including the endocannabinoid system, which plays a key role in calming overactive nerves, controlling inflammation, and maintaining balance in brain signalling. When this system does not function optimally, pain signals can become amplified and prolonged, contributing to both the intensity and duration of migraine attacks. Cannabinoid-based medication works by interacting with this system, helping reduce nerve overactivity, modulate pain transmission, and limit inflammation. 

Today, migraine is understood as a brain network disorder, not simply a blood vessel problem.

Triggers do not cause migraine by themselves; they overload an already sensitive brain. Common triggers include:

• Weather changes, especially shifts in pressure or temperature

• Skipping meals, dehydration, alcohol, fermented or aged foods, excess caffeine

• Hormonal fluctuations, particularly changes in estrogen

• Chronic stress or sudden stress release

• Poor or irregular sleep

• Bright lights, loud noise, strong smells, prolonged screen exposure

Triggers often add up, with multiple small factors pushing the brain past its tolerance limit.

Migraines occur because the brain is wired to be more sensitive to changes. Genetics shape this sensitivity, brain chemicals and nerves drive the pain, and everyday triggers determine when attacks occur. Migraine is not a personal failing and not “just a headache.” Understanding the science behind it helps people recognise early signs, manage triggers more effectively, and make informed decisions about long-term care.

Also Read:

• What is Migraine?

• Understand Migraine Symptoms and Causes for Better Prevention

• Is Migraine Curable?