Migraine and light: when brightness hurts

Many people with a migraine will try to get out of the light. Often they have no choice but to go into a dark room and wait for the attack to end. Increased sensitivity to light is common in people with migraine. For some, light can even trigger an attack. This article explores how this happens and what the science says.

Discovered in ancient Greece

“Photophobia” is the medical term for when bright lights hurt your eyes. The word literally means "fear of light" (Greek phos, photos: light; phobos:fear). Photophobia is not an actual phobia, though, but an abnormal visual intolerance to light.

It was first described by Aretaios of Cappadocia (ca. 30-90 AD, according to other sources ca. 80-130 AD), a Greek physician and follower of Hippocrates, the acknowledged father of modern medicine. It is thought that Aretaios himself had migraine, so he may have discovered the link between light and migraine from personal experience. Aretaios was also one of the first to describe different types of headaches. His accounts of headache and other nervous system disorders were so thorough and knowledgeable that he preempted some of the explanatory approaches of the 19th and 20th centuries.

What does the science say?

Centuries after Aretaios, about 90 years ago, James E. Lebensohn described what he called "true photophobia" in the terms of modern science: “exposure of the eye to light definitely induces or exacerbates pain”.

This strict definition was toned down later. “Discomfort or pain triggered by very bright light or light perceived as excessively bright” is the usual understanding today. The sensation is not always painful, but many people still feel a strong urge to escape to a dark room. This discomfort caused by light is considered a subtype of photophobia.

Light sensitivity can manifest itself in three ways, each of which can affect the others:

• Light-induced exacerbation of headache

• Extreme light sensitivity/intolerance of light

• Discomfort caused by light

Migraineurs are exceptionally sensitive to light

Up to 80% of migraine patients are affected by light sensitivity, both during and between attacks. Light can even trigger migraine attacks.

Science has found that certain parts of the migraine brain are exceptionally sensitive to stimuli. Especially light, but brain areas involved in the perception of pain, sound, smell, and taste are also more sensitive than in people who do not get migraine. This could explain the increased responsiveness of migraineurs to sensory input.

How does light lead to a migraine headache?

And how does sensitivity to light turn into pain? How exactly does exposure to light trigger a migraine headache? Theories have been proposed to explain how light sensitivity results in a migraine headache. However, there is no one single explanation that all medical experts can agree on. A number of structures and signaling pathways are probably involved, mainly in the nervous system.

Light stimuli and the trigeminal nerve

One explanation is based on the theory that light stimuli activate certain parts of the trigeminal nerve in the brain. The signals involved come from special sensory cells in the retina of the eye. Various processes might then trigger pain perception.

1. The activated sensory cells directly trigger pain in the trigeminal nerve

2. Other connections with nerve cells in the diencephalon (interbrain) result in the release of neurotransmitters. These widen the blood vessels in the meninges and might also be responsible for inflammatory processes there. A process of this nature has long been considered a key factor in causing a migraine attack.

3. The neurotransmitters themselves amplify pain perception.

Researchers suspect that these different mechanisms interact with each other. In addition, other signaling pathways may be involved that are not well understood yet.

Can you protect yourself from light stimuli?

There are a lot of conflicting theories around light sensitivity in migraine, and equally conflicting advice about how to manage it. One approach is to reduce exposure to the incident light that triggers the stimulus (or the light component responsible for the stimulus). Skilled opticians will be able to provide glasses with specially treated, anti-reflective lenses that reduce direct and reflected light (glare) from surfaces such as water, snow or sand; make aggressive UV radiation harmless; and protect the eye from the glare of bright sunlight.

Replacing the light bulbs in your home with ones that generate warm white light may help too. The ‘color temperature’ of your light bulbs should be between 2000 and 3000 Kelvin. 2700 Kelvin is a popular choice.

The best approach to migraine prevention is holistic: stress reduction, good sleep and screen breaks

Successful prevention means looking at all the ways migraine impacts the body and mind and how these things interconnect. One trigger often influences another. Stress and lack of sleep are known to make light sensitivity worse in migraineurs. While you may not be able to cut stress out of your life completely, there are things you can do to offset its effects. You can try rescheduling your day to build in mindful moments of relaxation. Regular, restful sleep is key to migraine prevention. Look at your sleep habits in detail and explore ways to ensure a healthy balance. It’s worth it.

Staring into a computer screen and using mobile phones, tablets and other devices can make your light sensitivity worse. Try reducing your daily screen time. Regular screen breaks are important. It undoubtedly takes guts to tackle these challenges. But the reduction in migraine attacks is well worth the effort.