Migraines are a recognised neurological medical condition. They include various autonomic nervous system symptoms including headache, nausea, photophobia, vomiting, numbness or paresis, and sensitivity to noise and smell.
Migraines are generally accepted to be a neurovascular condition with the latest research considering that it starts with cortical depression spreading to the vascular system.
Migraine can be preceded by various symptoms during the prodromal phase.
These prodromal symptoms most commonly include a visual aura. This can
involve a flickering zig zag light which usually enlarges over several
minutes, a scotoma or patchy loss of vision, and hallucinations. The
symptoms generally progress in severity over several minutes.
Prodromal symptoms can also include difficulty speaking and thinking (known as aphasia), and confusion. Some migraine sufferers also notice a tingling sensation in parts of their body as well as irritability and fatigue. Sometimes these symptoms can occur in isolation without a progression of the migraine to the acute headache phase.
If the migrainous episode progresses to a headache, this usually affects one side of the head and typically begins above the eyes. The pain is generally severe and throbbing and can have a duration between 3 hours to 3 days.
Although the cause of migraine is uncertain, it is thought to have both a genetic and enviromental component. Some researchers postulate that it can be related to low levels of serotonin. There also seems to be contributing physiological factors such as diet, stress and fatigue.
Several years ago Harvard researchers discovered that specific wavelengths of light caused intensified pain in migraine sufferers. They postulated that "the mechanism of photophobia must involve the optic nerve, because in totally blind individuals, the optic nerve does not carry light signals to the brain." Subjects in the group were found to be particularly sensitive to short wavelengths like blue or grey. They also stated that "We also suspected that a group of recently discovered retinal cells containing melanopsin photoreceptors (which help control biological functions including sleep and wakefulness) is critically involved in this process".