In the middle of an electronic dance music festival in Amsterdam, a 20-year-old man suddenly collapsed. Just before he seized and bit his tongue, he told his friends he was experiencing a strange and discomforting “aura-like” experience and felt a strong urge to turn his eyes away from the strobe lights onstage. As a study published Tuesday in BMJ Open reveals, hospital tests confirmed he was epileptic, even though he had never experienced a seizure before.

The new study establishes that what happened to the young man is far from rare: Strobe lights, the researchers write, are likely linked to a tripling in the risk of epileptic fits in susceptible individuals.

"I decided to to take on this question and find out if this was a frequent problem during festivals."

Nèwel Salet, the paper’s first author and a Ph.D. candidate at VU University Medical Center Amsterdam, learned about the case from an internal medicine specialist who told him about a patient coming in with what looked like a photosensitive epileptic insult after visiting an EDM festival. At the time, he was looking for something “out of the box” to examine as his master’s thesis. Salet hypothesized that the patient wasn’t likely the first to have this experience.

“However, no literature existed on this particular subject,” he tells Inverse. “I decided to to take on this question and find out if this was a frequent problem during festivals.”

A particular form of epilepsy, called photosensitive epilepsy, has a well-established link to seizures that are triggered by flashing or flickering lights. However, it’s not common, and as the young man’s case demonstrates, a person might not know they have the condition until they come into contact with a trigger. About one in 100 people have epilepsy — and within this group, just 3 percent have photosensitive epilepsy.

People are more likely to seize during a nightime EDM show with strobe lights than a daytime show. Unsplash / Aditya Chinchure

Salet and his colleagues got in touch with a company that provides medical services to dance festivals in the Netherlands, from whom they received data profiles attached to 400,343 people who attended at least one of 28 EDM festivals in the Netherlands in 2015. Within this group, medical assistance was provided on 2,776 occasions. In 39 cases, this was because of an epileptic seizure, and 30 of those seizures took place during nighttime gigs.

These gigs were the ones where strobe lighting was used. But the team questioned whether or not strobes were the singular triggers of the seizures — a handful of the people who had seizures reported that this was the first time they had ever experienced something like that, demonstrating the fact that every individual has a different tolerance for various risk stimuli.

They examined whether or not other factors may have enhanced the tendency to develop seizures. But as they examined the relationship between components like sleep deprivation, age-related susceptibility, and the use of ecstasy, they found that the people who attended the daytime shows — and did not experience seizures — were equal participants in those factors. The researchers write that it “was not possible to fully disentangle the individual components of epileptogenic circumstances.”

People were less likely to experience epileptic seizures during day raves. Unsplash / Eric Ward

But strobe lights still seem like a highly likely offender.

When the team examined the incidence density ratio of epileptic seizures in exposed individuals (people who saw strobe lights) and unexposed (people who did not) they found that exposed people were 3.5 percent more likely to undergo a seizure.

"…we strongly believe strobe lights to be the main culprit in provoking epileptic insults during these festivals."

“By dividing our cohort with the goal of valid comparison between case and control [both groups use drugs, same age group, the same type of festival], we tried to adjust uncertainty to the best of the data possibility,” Salet says. “Although there might be more contributing factors, we strongly believe strobe lights to be the main culprit in provoking epileptic insults during these festivals.”

The study was enough to convince the team that, regardless of whether strobe lights are solely responsible, EDM festivals, especially the ones that take place at night, “probably cause at least a number of people per event to suffer epileptic seizures.” Salet says that it’s not the mere fact this happens that’s so surprising — what’s surprising is that it happens so often.

The team hopes that festival organizers step up and start to routinely warn audiences about the possible dangers of taking in a show, and they hope that the general public starts to become more mindful about what could happen at a show. Unnecessary seizures can be prevented, but it takes knowing what the risks are to lessen the chance of them happening.

Abstract:

Objectives: Electronic dance music (EDM) concerts are becoming increasingly popular. Strong stroboscopic light effects are commonly part of these shows, and may provoke seizures in individuals with photosensitive epilepsy. This study aims to examine the risk of epileptic seizures during EDM concerts.

Setting: 28 EDM concerts taking place in The Netherlands.

Participants: We describe a young man who experienced a seizure during an EDM concert, and who later showed a positive electroencephalographic provocation test during exposure to video footage of the same concert. Subsequently, we performed a cohort study of 400 343 visitors to EDM concerts, divided in those exposed (concert occurring in darkness) versus unexposed (concert in daylight) to stroboscopic light effects.

Results: In total, 400 343 EDM concert visitors were included: 241, 543 in the exposed group and 158,800 in the control group. The incidence density ratio of epileptic seizures in exposed versus unexposed individuals was 3.5 (95% CI: 1.7 to 7.8; p<0.0005). Less than one-third of cases occurred during the use of ecstasy or similar stimulant drugs.

Conclusion: Stroboscopic light effects during EDM concerts occurring in darkness probably more than triple the risk of epileptic seizures. Concert organizers and audience should warn against the risk of seizures and promote precautionary measures in susceptible individuals.