Fatal familial insomnia: a genetic condition where people never sleep again

A woman in shown lying on her side in bed. She is awake and staring into the distance. Natural light appears to be streaming across her face. .

Disease name: Fatal familial insomnia (FFI)

Affected populations: The disease affects an estimated 1 to 2 people per million every year, according to the National Organization of Rare Disorders. FFI is passed from parent to child, and between 50 and 70 families worldwide are believed to carry the genetic mutation that causes FFI. Males and females are equally likely to develop the condition.