The Lavender Town Syndrome was a peak in suicides and illness of children between the ages of 7-12 shortly after the release of Pokémon Red and Green in Japan, back in February 27, 1996.
Rumors say that these suicides and illness only occurred after the children playing the game reached Lavender Town, whose theme music had extremely high frequencies, that studies showed that only children and young teens can hear, since their ears are more sensible.
These were just rumors and were not proven to be true, however given certain circumstances children playing with headphones did receive headaches. The game which had these high frequencies was quickly taken off the market.