Death by electric fan
 

Fan death is an urban legend that originated in South Korea, but has since spread to other countries in the Far East. The belief is that an electric fan, if left running overnight in a closed room, can result in the death (by suffocation, poisoning, or hypothermia) of those inside. This belief also extends to air conditioners and the fans in cars. When the air conditioner or fan is on in a car, some people are apt to leave their car windows open a crack to avoid "fan death." Fans manufactured and sold in Korea are equipped with a timer switch that turns them off after a set number of minutes, which users are frequently urged to set when going to sleep with a fan on.

http://en.wikipedia.org/wiki/Fan_death

I hope they dont lay down when they sleep, that might couse their heads to explode :D