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Fatal Familial Insomnia: Symptoms, Diagnosis, and Treatment

Although many people experience insomnia, most are able to get some amount of shuteye. However, a rare and serious condition known as fatal familial insomnia causes people to lose the ability to sleep over a period of time1.

As humans, we need sleep to function, which means the ramifications of this disease are deadly2. In this article, we will go into detail about fatal familial Insomnia, including the symptoms, who is at risk, and what to do if you suspect that you have it.

What Is Fatal Familial Insomnia?

Fatal familial insomnia is a degenerative brain disorder that inhibits a person’s ability to fall asleep. According to experts3, insomnia symptoms continue to worsen over time. People with this condition can also experience impairments in their autonomic nervous system, which is responsible for automatic bodily functions such as heartbeat, breathing, or sweating.2

How Do You Get It?

Fatal familial insomnia can be inherited genetically, and it develops when there is an abnormal variant in the PRNP gene. The PRNP gene is responsible for the production of the prion protein, an active protein in the brain.2

When the gene sends abnormal signals, it can lead to malformed — and toxic — prions. The accumulation of these toxic prions can cause a decrease in nerve cells4, which is what causes insomnia and associated symptoms.

People inherit this disease in a gene pattern known as autosomal dominant.2 In our DNA, we inherit two copies of each gene. Autosomal refers to when the particular gene is found on a numbered, non-sex chromosome5, and dominant means that only a single copy of a mutated gene is needed to carry the disease. Conversely, recessive genetic disorders need two mutated copies to pass along a disease.5

In the case of FFI, this means that only one parent would need to pass on the gene for someone to inherit the disorder.

Want to know more? Find out how genes influence insomnia.

Sporadic Fatal Insomnia

Not all cases of fatal insomnia are inherited, though. Specifically, scientists say that sometimes a person can develop a spontaneous genetic mutation affecting the prion protein, known as sporadic fatal insomnia6. Both the sporadic form and familial insomnia are rare human prion diseases.

Additionally, prion diseases may result from a person’s environment. For example, some research suggests that one way to acquire a prion disease is through iatrogenic exposure7, which is when your condition stems from medical care.


Scientists officially named this rare disease fatal familial insomnia in 1986. An Italian family8, who had passed down the disease through generations spanning 200 years, provided researchers with a substantial amount of details when one of the members, Silvano, decided to go public with their family history of this condition.

The scientists were able to study Silvano and his symptoms during his last few months alive. Unfortunately, he passed away in 1984 at the age of 53, but his contributions to the study of fatal familial insomnia remain impactful to this day.8

Fatal Familial Insomnia Symptoms

Fatal familial insomnia symptoms usually begin between the ages of 20 and 61, and the disease has an average duration of 18 months.2


Insomnia is one of the primary symptoms of this disease.2 

We mentioned earlier that fatal familial insomnia leads to a loss of nerve cells – or neurons – in the brain.4 The neuron loss is primarily centered in the thalamus, the part of the brain that regulates the body’s natural sleep-wake cycle, which means this disease’s effect on the thalamus is what ultimately causes people to experience this extreme insomnia.2

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Cognitive Impairment

If you’ve experienced even just one night of sleep deprivation, you are probably all too familiar with how it leaves you feeling as though you are in a brain fog the following day. Unfortunately, after multiple nights of little to no sleep, this only continues to worsen. Much like regular insomnia, fatal familial insomnia will cause diminished cognitive abilities, including difficulty concentrating, slower thought processes, and short-term memory loss.2

Weight Loss

Someone with fatal familial insomnia may also experience weight loss.2 In fact, weight loss is part of the criteria for diagnosing FFI. People must experience either weight loss exceeding 10 kilograms in the last six months and/or certain vegetative symptoms like hyperhidrosis, tachycardia, obstipation, and hyperthermia.2 

Poor Coordination

Difficulty coordinating your body movements is another symptom of fatal familial insomnia.2 

In some cases, a person may experience a complete loss of coordination, known as ataxia9. This loss of coordination reveals itself in various ways, possibly affecting balance, walking, speaking, writing, swallowing, and vision. People who have had a stroke, multiple sclerosis (MS), or a brain tumor may also develop ataxia. When this happens, it is known as acquired ataxia.9

High Blood Pressure

Those with fatal familial insomnia may present symptoms related to autonomic dysfunction, including high blood pressure.2 Blood pressure measures the pressure of your blood against the walls of your arteries. When that pressure grows too much, this is referred to as high blood pressure10.

Health experts say many individuals may not feel the effects of high blood pressure apart from headaches, shortness of breath, or nosebleeds. However, high blood pressure can be a dangerous health condition because it could eventually lead to serious health complications such as heart attack, stroke, aneurysm, heart failure, impaired blood vessels, metabolic syndrome, cognitive difficulties, and dementia.8

Unable to Maintain Body Temperature

People with fatal familial insomnia can also have trouble maintaining stable, healthy body temperature patterns.2 According to research11, this disease can affect a person’s circadian rhythms, natural body clocks that regulate sleep-wake patterns.

Circadian rhythms prepare the body for sleep, and an example of this is lowering the body’s core temperature. However, people with fatal familial insomnia typically have elevated core body temperatures, which may further explain their disconnect from sleep.11

Profuse Sweating and Crying

A person may also see an increase in the production of sweat and tears resulting from fatal familial insomnia.2 Earlier, we mentioned Silvano, an Italian man who had this disease and a family history of it. Excessive sweating was one of the other symptoms he developed in addition to insomnia.8

Diagnosing Fatal Familial Insomnia

To diagnose fatal familial insomnia, a doctor will first review your symptoms. From there, the physician may perform a clinical exam and refer to a sleep specialist to undergo a sleep study, or polysomnography12.

A polysomnography is used to help diagnose various sleep disorders. During this test, the sleep specialist will hook you up to equipment that measures your brain waves, blood oxygen levels, heart rate, breathing, and leg and eye movements while you are asleep. Sleep tests can either be provided in a clinic or at home.12

Since this is an inherited disease, genetic testing may confirm whether the individual has fatal familial insomnia. In some cases, the person may already know a family member who has had this condition. Genetic testing involves looking for variations or mutations in your DNA13.

Treatment Options

There is no known cure for fatal familial insomnia. As a result, treatment of this disease focuses on mitigating symptoms to help the individual feel as comfortable as possible.2

The patient may be recommended to see a team of specialists, including a neurologist, medical geneticist, and counselor. The rare status of this disease means you may need to reach out to universities, national, or even international outlets to find healthcare professionals who specialize in this field.

Emerging Science

Currently, an ongoing study is looking to see if the drug doxycycline, which is normally used to treat bacterial infections, could be a preventative treatment14 for fatal familial insomnia. The study began in 2015 and participants who have a genetic risk for developing FFI will be taking doxycycline for 10 years.

Other Neurological Sleep Disorders

Fatal familial insomnia is one type of neurological sleep disorder. However, there are additional sleep disorders caused by neurological issues15.

Central Sleep Apnea

Central sleep apnea is a disorder in which a person’s breathing continually starts and stops while asleep. The reason for this is that the brain cannot send the correct signals to the airway muscles16, which causes gaps in breathing. Another form of sleep apnea, obstructive, is more common due to a physical blockage in the airway’s path.

Circadian Rhythm Disorders

Circadian rhythm disorders occur when the body’s internal clock regulating the sleep-wake cycle does not work properly. As a result, people with these disorders have trouble falling asleep, staying asleep, or waking up too early.


Narcolepsy is characterized by extreme tiredness and suddenly falling asleep. Additional symptoms can include muscle tone toss, sleep paralysis, rapid eye movement (REM) sleep changes, and hallucinations.

Experts do not know the exact cause of this disorder but say that people with narcolepsy17 often have low hypocretin levels in the brain. Hypocretin is a chemical that is responsible for controlling wakefulness and REM sleep.17


Parasomnias are unusual behaviors that interrupt sleep. Examples of this include sleepwalking, talking in your sleep, and sleep paralysis. Parasomnias18 may result from neurological sleep disorders like narcolepsy and circadian rhythm disorders.

REM Sleep Behavior Disorder

REM sleep behavior disorder involves the sleeper acting out bad dreams. Normally, people lose their ability to move during REM sleep to keep them safe since we usually dream during REM sleep. However, experts hypothesize19 that REM sleep behavior disorder may be linked to neurological conditions.

Frequently Asked Questions

Is fatal familial insomnia common?

Fatal familial insomnia is a highly rare disease.2 It’s estimated that fewer than 1,000 Americans20 have it.

How long can you survive FFI?

Unfortunately, without a cure, this disease is fatal to those who have it, and researchers say the average duration someone may live with it is 18 months.2

Fatal familial insomnia is broken down into four stages.2 However, these timelines can vary according to each individual’s particular case. Therefore, consider this a general blueprint timeline.

Stage 1

During the initial stage, the individual will begin to experience acute insomnia, which will worsen over the following few months. Sleeplessness is expected to lead to psychiatric side effects such as phobias, paranoia, and panic attacks. Lucid dreaming may also occur.2

Stage 2

The following stage typically lasts for about five months. During this time, the individual’s sleep capability will continue to decline, and their psychiatric symptoms will worsen. Additionally, the deterioration of autonomic functions may cause hyperactivity of the sympathetic nervous system. Examples of this hyperactivity can include increased heart rate, rapid breathing, and high blood pressure.2

Stage 3

The third stage usually goes on for about three months. Stage 3 tends to see a complete lack of sleep and disruptions to the individual’s sleep-wake cycle.2

Stage 4

The fourth and final stage of fatal familial insomnia will typically last six months or longer. At this time, the individual will see the swift collapse of their cognitive abilities and the emergence of dementia.2

Furthermore, they will likely no longer be able to move on their own and have speech problems. Next, the individual will likely enter into a coma shortly before death.2

What’s the difference between fatal familial insomnia and regular insomnia?

Fatal familial insomnia and traditional Insomnia may share similar titles, but the two have significant differences. Fatal familial insomnia is a rare neurological disorder that an individual inherits from a family member.1 Insomnia, on the other hand, is a sleep disorder that is typically caused by lifestyle factors21 such as travel and work schedules and bad sleeping habits. However, certain medical conditions, mental health issues, advanced aging, and other sleep disorders can also lead to insomnia.21

Unlike fatal familial insomnia, regular insomnia is more common, and it is a treatable condition. In addition to limited sleep, fatal familial and regular insomnia share some other symptoms as well. For example, people with insomnia can also experience impaired cognitive abilities.21

Jill Zwarensteyn

Jill Zwarensteyn


About Author

Jill Zwarensteyn is the Editor for Sleep Advisor and a Certified Sleep Science Coach. She is enthusiastic about providing helpful and engaging information on all things sleep and wellness.

Combination Sleeper

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