On December 16, 1997, a mysterious plague swept through Japan: in a single evening, some 12,000 people reported symptoms ranging from nausea to seizures, and nearly 700 — mostly school kids — were rushed to the hospital. The reason: they had all viewed an episode of the popular anime cartoon Pokemon featuring about 5 seconds of flashing red and blue lights. The combination can trigger seizures in people with photosensitive epilepsy. (The reason for the nausea or dizziness is less clear; some analysts suspect it stemmed from anxiety provoked by early media coverage of the event.) The following day, TV Tokyo issued an apology and suspended the program. Not long after, Japanese broadcasters teamed up with medical officials to create new guidelines for animated programs, limiting the speed at which images flash, among other changes. Two viewers stayed in the hospital for more than 2 weeks.