Everything You Need to Know About Fatal Familial Insomnia

If you struggle with insomnia, you may have wondered how long you can go without sleeping. You may be relieved to hear that new evidence shows typical insomnia won’t shorten your life. 

But there’s one type of insomnia that leads to death. It’s called “fatal familial insomnia,” and it’s incredibly rare. Let’s take a closer look at this unusual condition. 

What causes fatal familial insomnia?

Even though it has “insomnia” in its name, fatal familial insomnia isn’t a sleep disorder. 

Fatal familial insomnia is a type of brain illness that prions cause. Prions are misfolded proteins that can “infect” or transfer their misshapen forms onto normal proteins. When this happens, a person develops a prion disease.

Prion diseases lead to damage in the brain. In fatal familial insomnia, the thalamus and medulla oblongata (parts of the brain) slowly start to break down and eventually die. As this happens, people experience symptoms of fatal familial insomnia. The symptoms get worse as the brain gets sicker.

How common is fatal familial insomnia?

Fatal familial insomnia is extremely rare. People with fatal familial insomnia form prions because of a genetic mutation in their PRNP gene. 

That means fatal familial insomnia passes down from generation to generation within families. Only about 70 families in the entire world carry the mutation for fatal familial insomnia.

Very rarely, someone who doesn’t have the PRNP gene mutation can develop the prion disease that causes fatal insomnia. This is called “sporadic fatal insomnia” to differentiate it from fatal familial insomnia. But despite the differences in names, the symptoms and outcomes are the same. Only about two dozen cases of sporadic fatal insomnia have been reported.

What are the symptoms of fatal familial insomnia?

The most common symptom of fatal familial insomnia is a sleep disturbance — mainly trouble sleeping and insomnia. Other symptoms include:

• Daytime sleepiness

• Rapid onset of dementia and memory loss

• Fast heart rate

• Excessive sweating

• Muscle spasms

• Seizures

• High blood pressure

• Double vision

• Sexual dysfunction

• Constipation

• Mood changes

• Weight loss

People usually develop symptoms between 50 and 60 years old. Symptoms tend to get worse over 6 to 12 months. 

As time goes on, people have difficulty with balance and walking. And they develop more severe dementia, confusion, and even hallucinations. Within about 1 to 3 years, people die from this condition. 

It’s important to point out that the early symptoms of fatal familial insomnia aren’t specific and can happen with many other conditions. So if you’re experiencing trouble sleeping, talk to your healthcare provider. It’s likely that there’s a different, more common reason for your symptoms.

How do you diagnose fatal familial insomnia?

Diagnosing fatal familial insomnia can be challenging because the condition is so rare. And the symptoms can be similar to those in other conditions. 

Experts developed a set of criteria that helps determine which people should have testing for fatal familial insomnia. If someone meets these criteria, healthcare providers will order tests to confirm the diagnosis. These tests can include: 

• Magnetic resonance imaging (MRI) of the brain 

• Cerebral spinal fluid testing 

• Electroencephalogram (EEG)

• Positron emission tomography (PET scan)

• Genetic testing for PRNP gene mutations

Is there a cure for fatal familial insomnia?

There’s no cure for fatal familial insomnia. As the name implies, there’s no way to survive the condition. On average, people live with the condition for 18 months. 

Medication can help ease symptoms. Healthcare providers can offer medication to help manage seizures and muscle spasms. Sleep aid medication can be helpful for some people with fatal familial insomnia, but it doesn’t work for everyone.