Fatal familial insomnia is a rare genetic disorder. It causes sleep problems and brain damage that eventually lead to death.

While it is characterized by difficulty sleeping, the disorder can cause a wide range of other symptoms, such as muscle spasms and problems with memory and thinking.

A genetic abnormality causes fatal familial insomnia. Another condition, called sporadic fatal insomnia, is similar but occurs without the genetic difference.

This article describes fatal familial insomnia, including its symptoms, diagnosis, and treatment options.

a woman having a sleep test for Fatal familial insomniaShare on Pinterest
A doctor may monitor brain activity during sleep to diagnose fatal familial insomnia.

Fatal familial insomnia is a rare disorder that causes difficulty sleeping and brain damage. These issues worsen over time.

It remains unclear how many people have fatal familial insomnia. It is one of a group of health issues called prion disorders, which affect around 1 in 1 million people each year.

Fatal familial insomnia stems from a genetic abnormality that leads to the death of neurons in the brain. It can also cause problems with functions such as the body’s regulation of temperature.

The primary symptom of fatal familial insomnia is difficulty falling or staying asleep. When someone with the disorder does sleep, they may experience vivid dreams and muscle spasms or stiffness.

The characteristic lack of sleep and brain damage can cause a wide range of other symptoms, including:

  • sweating
  • a fever
  • high blood pressure
  • a rapid heart rate
  • weight loss
  • sexual dysfunction
  • a loss of temperature control
  • memory problems
  • difficulty thinking and concentrating
  • speech problems
  • double vision or jerky vision
  • mood or anxiety disorders
  • trouble swallowing
  • muscle spasms or shakes
  • a loss of coordination

The symptoms are typically mild at first. Eventually, the disorder can entirely prevent sleep.

People with severe symptoms may enter a coma, which can lead to death.

Fatal familial insomnia develops due to an abnormality in the prion-related protein (PRNP) gene, which produces prion proteins. Researchers understand that these proteins are active in the brain, but their exact function is still unclear.

Mutation of the PRNP gene occurs in people with fatal familial insomnia. The mutation causes PRNP to produce faulty, or “misfolded,” prion proteins.

These misfolded proteins harm the nervous system, including the brain. There is particular damage to the thalamus, a region of the brain that plays a role in regulating sleep, appetite, and body temperature.

Over time, the misfolded proteins collect in the thalamus, causing the symptoms of fatal familial insomnia to develop and become increasingly severe.

Because fatal familial insomnia is so rare, there is little information about its risk factors.

Most people with the PRNP gene mutation start to experience symptoms around the ages of 45–50.

A doctor first asks about the person’s symptoms, especially their sleep habits.

They may ask the person to keep track of their sleep patterns and any disruptions in a diary, as this information can help the doctor make a more informed diagnosis.

The doctor may also suggest a polysomnography test. This usually involves spending the night at a sleep center or hospital. During the night, doctors monitor brain activity, respiration, and eye or leg movements.

If they suspect fatal familial insomnia, a doctor might also use a PET scan, which records activity in the body’s tissues and organs. This type of scan can detect abnormalities in the thalamus.

In some cases, a doctor may use genetic testing to check for the characteristic PRNP gene mutation.

Fatal familial insomnia is so rare that doctors may not detect every case. Some people with the disorder may receive a diagnosis of a more common condition, such as dementia.

There is currently no cure or effective treatment for fatal familial insomnia. It may be possible to treat some of the symptoms, however. For example, a doctor may prescribe clonazepam (Klonopin) to treat muscle spasms.

Sleep medications may provide some temporary benefits. For example, eszopiclone (Lunesta) and zolpidem (Ambien) can help treat insomnia.

However, these drugs do not work in the long term.

People who develop fatal familial insomnia typically live 7 months to 3 years after the symptoms appear, though some people live longer.

The symptoms are mild at first and may not impact day to day activities.

As sleep problems worsen and other symptoms develop, these activities become more challenging. The doctor will recommend treatments for specific symptoms and other ways to improve the person’s quality of life.

During the later stages of the illness, a person may require regular care.

Fatal familial insomnia is a very rare genetic disorder. It causes sleeping problems and brain damage that become increasingly severe and lead to death.

The disorder can cause a range of other symptoms, such as problems with memory and trouble swallowing.

There is currently no cure for fatal familial insomnia. However, there are treatments for specific symptoms, such as muscle spasms.

People with fatal familial insomnia tend to live between 7 months and 3 years after the symptoms become apparent.