Narcolepsy is both a sleep disorder and a neurological disorder. The condition stems from changes in your brain that affect your sleep-wake cycles.

Overall, about 1 in 2,000 people in the United States may have narcolepsy. The actual number of people who it affects may be higher. This is because the symptoms can be similar to other sleep disorders, such as obstructive sleep apnea.

At first, narcolepsy often causes issues with sleeping at night, along with problems staying awake during the day. You may also develop other symptoms, such as sudden muscle paralysis. Symptoms like this can make it difficult to accomplish daily tasks.

Like other neurological conditions, the brain’s role in narcolepsy is complex. Researchers are still learning more about it. But it’s important to gain knowledge about how narcolepsy affects your brain so you can better understand the condition.

Narcolepsy develops as a result of changes in the hypothalamus region of your brain. This small gland is located above your brain stem.

The hypothalamus helps regulate the release of hormones that affect numerous parts of your body. For example, it’s responsible for releasing hypocretins, which help regulate sleep.

Aside from regulating your sleep cycles, the hypothalamus also plays a role in the following processes:

  • appetite
  • blood pressure
  • body temperature
  • electrolyte balances
  • emotions
  • heart rate

A rare form of narcolepsy can develop as a result of damage to the hypothalamus from a brain injury. This is known as secondary narcolepsy.

Secondary narcolepsy is a severe neurological condition that can lead to irregular sleep cycles as well as memory loss and mood disorders.

Hypocretin neurons help regulate your sleep-wake cycles. These chemicals in your brain are at their highest levels when you’re awake. They naturally decrease during your normal bedtime.

But when you have narcolepsy, hypocretin releases are low. This causes disruptions during the daytime, such as excessive sleepiness and fatigue. You may also tend to take more naps during the day.

Reduced hypocretins are strongly linked to narcolepsy type 1. This type of narcolepsy includes:

  • disrupted sleep cycles
  • daytime fatigue
  • cataplexy (sudden loss of muscle control)

Hypocretin losses can also affect other brain hormones, such as serotonin. This can cause sleep paralysis and hallucinations when you wake up.

If you have type 2 narcolepsy, you may experience issues with sleep cycle regulation but don’t have issues with cataplexy.

The cause of type 2 narcolepsy is unclear. Some research points to fewer hypocretin injuries.

While the exact cause of narcolepsy is unknown, genetics may play a role.

One theory has found that people with narcolepsy share T cell receptor changes in their cells. These T cells are partially responsible for secreting antibodies when they encounter a virus or other invader in the body.

Another theory is that people with narcolepsy share a specific gene that prevents proper immune function.

Research estimates that between 12 and 25 percent of people have this gene, known as human leukocyte antigen (HLA) DQB1*06:02. However, having the gene doesn’t mean you’ll develop narcolepsy.

It’s also possible that narcolepsy is an autoimmune disease, which causes the body to attack its own healthy tissues instead of pathogens.

Narcolepsy type 1 has been found to include autoantibodies in the hypothalamus, which can directly attack hypocretins.

While narcolepsy itself isn’t typically passed from parent to child, autoimmune disorders do run in families. You may have a relative with an autoimmune condition, but not the exact same type.

The absence of hypocretins in your brain to regulate your sleep-wake cycles can lead to atypical sleep patterns. Normally, your nighttime sleep cycle starts with non-rapid eye movement (non-REM) sleep.

After about an hour, a typical sleep pattern enters the REM cycle. This cycle isn’t only known for rapid eye movements. Your muscles also go into paralysis.

You also experience more dreams during your REM cycles because you aren’t able to act them out due to your deep state of relaxation.

With decreased hypocretins, your sleep-wake cycles in narcolepsy cause you to enter REM sleep much more quickly. It also doesn’t last as long, which can make for a restless night’s sleep.

In addition, narcolepsy can lead to unexpected REM cycles during the daytime. These are also called “sleep attacks.”

Not getting enough good quality sleep at night can also lead to an extreme type of fatigue known as excessive daytime sleepiness. This is the primary symptom seen in both type 1 and type 2 narcolepsy.

With excessive daytime sleepiness, you may have trouble getting through the day at work or school. It can also make it dangerous to operate heavy machinery or other objects that can cause injury if you suddenly fall asleep.

Aside from disrupted sleep cycles and excessive daytime sleepiness, narcolepsy type 1 can cause cataplexy.

Similar to the muscle paralysis experienced during a REM cycle, cataplexy causes sudden loss of muscle coordination while you’re awake. Such events can come on suddenly, usually after experiencing a strong emotional reaction.

Other possible symptoms associated with narcolepsy include:

  • hallucinations
  • paralysis upon waking up in the morning
  • insomnia
  • sleep apnea
  • depression
  • concentration difficulties
  • memory problems

While not widely considered a progressive disease, one study suggests progression in people with early onset narcolepsy compared to those who develop the condition later in adulthood.

Progression could ultimately mean worsening symptoms over time. However, more studies need to be done to back up this research.

While sleep-wake cycles are often the focus of narcolepsy, all the possible symptoms of this condition stem from changes in the brain.

When the hypothalamus doesn’t release hypocretins as it should, issues with your sleep cycles will develop. This condition may also have a genetic component.

Regardless of the causes, narcolepsy can have a profound effect on your everyday life. A proper diagnosis is key to getting the treatment you need to help regulate your sleep-wake cycles.