Insomnia is a difficult condition for anyone to deal with at the best of times, but there is a variation of insomnia called sporadic fatal insomnia. It's an extremely a rare condition which physically affects an individuals ability to sleep. It does this to such an extent that every known case has proven fatal.

Unlike the more common type of insomnia that you or I may suffer from, sporadic fatal insomnia is not caused by external influences such as stress, anxiety, diet or other difficulties. Rather, it is an internal condition caused by a deficient protein called prion.

The prion interferes with the person's ability to sleep by affecting a particular area of the brain called the thalamus, which directly controls and influences sleep. It's called sporadic fatal insomnia because it can occur spontaneously in an otherwise healthy individual.

It's interesting, if slightly worrying, that the same defective gene responsible for sporadic fatal insomnia is the same one responsible for BSE, or so called mad cow disease.
Symptoms of sporadic fatal insomnia will usually begin to exhibit themselves in people between the ages of forty and sixty, although it has been found in people as young as thirty. Initially, the sufferer begins to have difficulty with sleeping, which progresses into trouble controlling their movement. The condition worsens fairly rapidly and eventually ends in dementia, with an increasing loss of ability to distinguish between dreams and reality.