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Fatal Insomnia

by Pierluigi Gambetti, MD

Fatal insomnia is a rare prion disease that interferes with sleep and leads to deterioration of mental function and problems controlling movements. Death occurs within a few months to a few years.

Fatal insomnia has two forms:

  • Familial: This form, called fatal familial insomnia, is inherited. It is due to a specific mutation in the gene for a normal protein called cellular prion protein (PrP C ).

  • Sporadic: This form occurs spontaneously, without a genetic mutation.

Fatal familial insomnia and sporadic fatal insomnia differ from other prion diseases because they affect predominantly one area of the brain, the thalamus, which influences sleep.

The familial and sporadic forms typically begin during a person's 30s. At first, people may have minor difficulties falling asleep and occasional muscle twitching, spasms, and stiffness. Eventually, they cannot sleep at all. Occasionally, the sleep problems are difficult to detect. Mental function deteriorates. Later, the heart rate may become rapid, blood pressure may increase, and people may sweat profusely. Death usually occurs about 7 to 73 months after symptoms begin.

Diagnosis and Treatment

The diagnosis of fatal familial insomnia is suggested by typical symptoms and a family history of the disease and can be confirmed by genetic testing.

To diagnose the sporadic form, doctors use polysomnography if the person has a history of sleep problems, Positron emission tomography (PET) is also done to check for abnormalities in the thalamus.

No treatment is available.