At least eight people suffered epileptic seizures at the same time during the recent Amsterdam Dance Event, according to organisers who are investigating if stroboscopic lights were partly responsible.

The incidents happened at around 5.50am on October 19, towards the end of a set by DJ De Sluwe Vos. People who attended the techno dance festival at Amsterdam’s Scheepsbouwloods said they had been left shaken and traumatised by the incident.

One witness told NOS how her friend had collapsed in front of her on the dance floor. ‘I can still see her coming towards me, in shock. We laid her on the ground in a foetal position. When I looked up, I saw eight groups of people standing round someone who was lying on the ground.’

Her friend, aged 18, said she had commented on the unusually bright lights at the event. ‘I said it earlier to a friend. Then at one point I suddenly woke up on the ground.’

The woman said she had taken two ecstasy pills during the evening, but had experience of using the drug. ‘I have been to nine techno festivals and never had problems with the lights. It’s not normal for so many people to collapse at the same time.’

Increased risk

Organisers admitted the episode was unusual but stressed that none of those who collapsed needed hospital treatment. Festival director Gerke de Groot told NOS enquiries were ongoing to see if a combination of tiredness, drugs and the bright lights had made epileptic seizures more likely.

‘Brief epileptic attacks have happened before at festivals and dance events. But to have so many so close to each other has never happened to us before,’ he said.

Esther Croes, spokeswoman for the Trimbos Institute, which specialises in mental health, substance use and addiction issues, confirmed that there was a higher risk of epilepsy associated with dance festivals. ‘An epileptic attack can be triggered by bright, rhythmic light. It’s not just people who are at risk who can be affected, people who are tired or have used drugs also run more risk.’

She added: ‘In cases like these it’s always difficult to establish the cause of an epileptic attack. What you can say is that the faster and brighter the lights, the greater the chance of a fit, especially in a darkened room.’

De Groot said he wanted to hear from those affected so the festival could investigate whether it needed to take preventive steps in future. Privacy concerns mean that emergency services are unable to disclose many details about the people they treated at the event, such as whether they all took the same drug.

He added he discussed the incident the next day with the lighting designer and technician. ‘In general we’re not a festival that uses a lot of stroboscopes or lasers, but for this techno festival it was a bit more intense than before.’