That an electric fan creates a vortex, which sucks the oxygen from the enclosed and sealed room and creates a partial vacuum inside.
That an electric fan chops up all the oxygen particles in the air leaving none to breathe.
The fan uses up the oxygen in the room and creates fatal levels of carbon dioxide.
That if the fan is put directly in front of the face of the sleeping person, it will suck all the air away, preventing one from breathing.
That fans contribute to hypothermia, or abnormally low body temperature.
That fans contribute to hyperthermia, commonly known as heatstroke.
As it happens, Fan Death is also a female, 2-piece electropop group that sounds like they listen to The Knife too much. I'm really hung over.