If asked to consider the association between epilepsy and light, people usually think of photosensitive epilepsy. Photosensitive epilepsy occurs in 1/500 people with epilepsy, and all (or almost all) of their seizures are triggered by flickering / flashing lights.

However researchers at the Institute of Neurology in London have now discovered a more positive link between light and epilepsy; in that light might actually lower the chance of a seizure occurring.

The group examined 1715 seizures recorded in a hospital neurology ward over 363 days in 2006/2007. Changing seasons are known to influence seizure frequency anyway, so the team had to factor for this in their analyses (to be sure that it was just the effect of sunlight that they were measuring).

The results showed that complex partial seizures were less likely to occur on bright sunny days than on dull days. Generalised and simple partial seizures loosely followed this pattern, but not to a significant degree. Interestingly, there appeared to be no relationship between hours of sunlight and non-epileptic seizures.
Click here to see a graphical summary of these findings

A lot of work is now needed to confirm the link between sunlight and seizures, and establish why it exists. However this early data is exciting, because it could open an avenue for a completely non-invasive light box treatment for certain people with epilepsy.

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