Secondary narcolepsy is a rare sleep disorder that occurs due to brain damage, specifically to the hypothalamus region. This part of the brain regulates the sleep-wake cycle.
People with secondary narcolepsy experience the typical symptoms of narcolepsy. However, they may also have other neurological problems and sleep for long periods of time, sometimes for
This article provides an overview of secondary narcolepsy, including its causes, symptoms, diagnosis, and treatments.
Secondary narcolepsy is a sleep disorder that occurs due to brain damage. It develops when the hypothalamus, which manages sleeping and waking, develops lesions. The hypothalamus is located deep inside the brain, near the brain stem.
The symptoms of secondary narcolepsy are similar to other types of narcolepsy. However, they can be more severe, depending on the nature of the brain injury.
Common symptoms include:
- excessive daytime sleepiness
- sudden episodes of muscle weakness, or cataplexy
- sleep paralysis
- neurological problems
- sleeping for extended periods of
10 hours or more
In addition to these symptoms, people with secondary narcolepsy may have other neurological symptoms.
The cause of secondary narcolepsy is an injury to the hypothalamus. This may occur if a person has experienced a head injury, though other things can also cause damage to this region of the brain. They
- an infection that damages or inflames the brain
- arteriovenous malformations
- demyelination, which is damage to the sheath that protects nerves
These injuries disrupt the functioning of the hypothalamus, resulting in secondary narcolepsy symptoms.
Secondary narcolepsy occurs because of damage to the hypothalamus. Primary narcolepsy does not. Scientists are less sure what causes primary narcolepsy, though a combination of autoimmunity and genetics may play a role.
Doctors divide narcolepsy into
Type 2 narcolepsy does not cause cataplexy and is often less severe than type 1.
People with secondary narcolepsy may have symptoms that more closely resemble type 1 or type 2.
When the condition is primary, there is no obvious brain damage. Instead, people with type 1 narcolepsy typically have a low level of a chemical known as hypocretin. This chemical helps to maintain wakefulness and regulates sleep-wake cycles.
Researchers believe primary narcolepsy with cataplexy may be the result of the immune system attacking healthy cells that make hypocretin, leading to a low level of the chemical. The cause of primary narcolepsy without cataplexy is unclear, as people with type 2 tend to have a typical hypocretin level.
The below table compares the symptoms of each type of narcolepsy:
|Primary narcolepsy type 1||Primary narcolepsy type 2||Secondary narcolepsy|
|Symptoms||cataplexy||no cataplexy||varies, though |
|Severity||more severe||often less severe||often more severe|
|Hypocretin level||low||often typical||varies|
Doctors typically conduct a physical exam and review the person’s medical history to diagnose secondary narcolepsy.
A doctor may also recommend polysomnography, or a
Secondary narcolepsy can look similar to other sleep disorders, such as primary narcolepsy or obstructive sleep apnea. Doctors may find it challenging to diagnose, and a person may wait years before they receive an accurate diagnosis.
If a person’s medical history and timeline of symptoms fit with this diagnosis, or they have distinctive symptoms that are not common in primary narcolepsy, a doctor may diagnose secondary narcolepsy.
Treatment for secondary narcolepsy may involve addressing the underlying cause of the disorder. This could include
However, this is not always the case. If a person has a TBI with lasting effects, the symptoms may persist.
- avoiding caffeine late in the day
- stopping or reducing alcohol consumption
- trying to stick to a consistent sleep schedule
- reducing stress
- getting regular exercise, though not in the hours before bedtime
Medications may vary depending on the person’s unique circumstances. Doctors may recommend sodium oxybate to those with cataplexy. They may also suggest certain antidepressants or stimulants.
Secondary narcolepsy is a sleep disorder that occurs when damage occurs in the hypothalamus, the area of the brain responsible for regulating sleep-wake cycles. This may occur following a TBI, stroke, tumor, or infection.
The main symptom is excessive daytime sleepiness. People may also experience sudden muscle weakness, hallucinations, sleep paralysis, and insomnia.
Diagnosis may involve imaging studies to look for underlying causes and sleep studies to evaluate sleep patterns.
Treatment for secondary narcolepsy may involve addressing the underlying cause and making lifestyle changes, such as avoiding caffeine and alcohol. Medications such as sodium oxybate, stimulants, or antidepressants may also help manage symptoms.