Although narcolepsy and schizophrenia are two different kinds of conditions, they can look alike and may be mistaken for one another. Although it’s not common, a person might have both narcolepsy and schizophrenia, making them comorbidities (co-occurring conditions).

The link between these two conditions is not fully understood, but they do have overlapping symptoms and may share similar causes. Doctors and researchers continue to study and learn more about how narcolepsy and schizophrenia are related. By becoming more familiar with the conditions’ connections, you can also better understand the associated risks and symptoms.

What Is Narcolepsy?

Narcolepsy is a sleep disorder that occurs when your brain has difficulty being able to tell when it’s time to sleep and when it’s time to be awake. This confusion can cause symptoms such as:

• Problems sleeping at night
• Rapid eye movement (REM) sleep occurring too quickly
• Hypersomnia (excessive daytime sleepiness)
• Sleep attacks (sudden episodes of sleep)
• Hallucinations (seeing or hearing things that aren’t there) because of confusion between dreams and reality.
• Cataplexy (sudden muscle weakness)
• Sleep paralysis (the inability to move when falling asleep or waking up)
• Sleep apnea (a condition that causes you to stop breathing while sleeping)

If you are living with narcolepsy, you may be all too familiar with the challenges that come with this often unnerving and disruptive neurological disorder.

What Is Schizophrenia?

Schizophrenia is a long-term psychiatric disorder that’s associated with psychosis, or feeling disconnected from reality. The symptoms of schizophrenia are divided into three categories — positive, negative, and cognitive:

• Positive symptoms — Behaviors or thoughts that people without schizophrenia don’t typically experience, such as disorganized thinking, abnormal body movements, auditory hallucinations (voices), and delusions (false beliefs)
• Negative symptoms — Behaviors that are decreased or missing in people with schizophrenia, such as social withdrawal, decreased emotions, and lower motivation
• Cognitive symptoms — Symptoms that affect how the brain works, such as difficulty thinking logically, learning new things, and making decisions

Causes of Schizophrenia

Researchers are still working to understand what causes schizophrenia. It’s thought that a combination of genetics, the environment, and the way your brain works all contribute to the development of schizophrenia.

People with a family history of schizophrenia are more likely to develop the condition. According to the National Alliance on Mental Illness, having a first-degree relative (a parent or sibling) with schizophrenia makes your chances of developing it six times higher.

Some researchers believe that an imbalance of the chemical messengers responsible for sending signals through your brain — specifically, glutamate and dopamine — leads to schizophrenia. Symptoms can be triggered or worsened by stress or substance use, especially the use of mind-altering drugs like marijuana.

Treatment of Schizophrenia

Although there is no cure for schizophrenia, the symptoms can be managed using several treatments, including:

• Medication — Antipsychotics and medications to manage other symptoms such as insomnia (difficulty sleeping)
• Psychotherapy and psychosocial therapy— Cognitive behavioral therapy, supportive talk therapy, and assertive community treatment (a team approach)
• Lifestyle adjustments — Trigger avoidance, improvement of social skills, employment-support programs, and family support

How Is Narcolepsy Related to Schizophrenia?

Right now, the connection between schizophrenia and narcolepsy is unclear. In fact, it’s rare to have both conditions. However, narcolepsy is sometimes misdiagnosed as schizophrenia because some symptoms of the two disorders resemble each other. Also, treatments for narcolepsy and schizophrenia can lead to side effects that look like the other disorder.

More research needs to be done on the causes of narcolepsy and schizophrenia to tell whether and how they’re actually related.

Narcolepsy and Schizophrenia Share Similar Causes

Researchers have suggested that people with narcolepsy may be more likely to develop psychiatric disorders such as schizophrenia. One study found that developing narcolepsy in childhood might put a person at a higher risk of developing schizophrenia later in life.

Some researchers believe that the link between narcolepsy and schizophrenia may be related to a loss of brain cells that make hypocretin (also known as orexin), a brain chemical that helps regulate wakefulness and sleep. People with type 1 narcolepsy — narcolepsy with cataplexy — may have low levels of hypocretin, leading to symptoms such as excessive daytime sleepiness.

Hypocretin is also thought to help control dopamine, a neurotransmitter (brain chemical) associated with motivation, reward, and pleasure. Schizophrenia affects levels of dopamine and other brain chemicals. In both narcolepsy and schizophrenia, low hypocretin levels have been linked to a particular gene subtype. The loss of hypocretin in people with narcolepsy could be related to changes in dopamine and other neurotransmitters that also contribute to the development of schizophrenia.

However, the association between narcolepsy and schizophrenia remains unclear, and more research is needed to understand this link.

Narcolepsy and Schizophrenia Share Similar Symptoms

When two conditions have many overlapping symptoms, telling them apart can be difficult. Doctors have described cases in which people with narcolepsy were misdiagnosed with schizophrenia.

For people who have type 1 narcolepsy, strong emotional reactions such as stress, anger, excitement, and laughter can trigger sudden loss of muscle control and weakness. Cataplexy symptoms range from mild to severe. In a mild case, you might notice your muscles twitching for no reason, while in a severe case, you may fall to the floor and be unable to speak or move.

Schizophrenia can lead to symptoms that are similar to cataplexy but are known as catatonia. For example, a person experiencing excited catatonia may also have uncontrolled muscle movements and twitches, while someone with withdrawn catatonia won’t show facial expressions or may not move for an extended period of time.

Hallucinations are also symptoms of both conditions. One study found that 80 percent and 81 percent of people with narcolepsy and schizophrenia, respectively, experience at least one hallucination. Narcolepsy tends to be associated with hallucinations that happen when falling asleep (hypnagogic hallucinations) or waking up (hypnopompic hallucinations). On the other hand, people with schizophrenia tend to have auditory hallucinations — hearing things that aren’t real.

Treatment Side Effects May Worsen Narcolepsy or Schizophrenia Symptoms

Researchers have also found that narcolepsy and schizophrenia treatments may make symptoms worse and make one condition look like the other. For example, people who take stimulants to treat their narcolepsy, such as modafinil (Provigil) or methylphenidate, may experience symptoms of psychosis similar to those of schizophrenia. In both narcolepsy and schizophrenia, antipsychotic medications can worsen symptoms such as excessive daytime sleepiness.

Diagnosing Narcolepsy and Schizophrenia

Because narcolepsy and schizophrenia share similar symptoms, your doctor will likely try to rule out one condition or the other, which is called a differential diagnosis. For a diagnosis of narcolepsy, they may run the following tests:

• Physical exam and medical history to learn more about your symptoms and risk factors
• Multiple sleep latency test (MSLT), which measures how long it takes you to fall asleep during the day and enter REM sleep
• Polysomnography, which measures brain signals while you sleep

Schizophrenia is diagnosed using the results of your physical exam, as well as a psychiatric evaluation with screening tests and questionnaires to rule out other conditions.

Talk With Your Doctor About Your Symptoms

Although there may be a link between narcolepsy and schizophrenia, there’s currently no evidence to suggest a direct relationship or that one condition causes the other. Remember that having narcolepsy doesn’t mean that you’ll develop schizophrenia and vice versa.

Talk with your doctor or mental health professional if you’re experiencing symptoms of narcolepsy or schizophrenia. They can determine whether you need to be evaluated for either condition and can help develop a treatment plan to manage your symptoms.

Find Your Team

MyNarcolepsyTeam is the social network for people with narcolepsy and their loved ones. On MyNarcolepsyTeam, more than 10,000 members come together to ask questions, give advice, and share their stories with others who understand life with narcolepsy.

Have you experienced symptoms of a psychiatric disorder because of narcolepsy? Have you talked with your doctor about your symptoms? Share your experience in the comments below, or start a conversation by posting on your Activities page.