“Narcolepsy takes your world and sort of flips it upside down.” – Scott

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The Science of Narcolepsy

There are three separate states of sleep and wakefulness.

Normally, states of sleep and wakefulness occur one at a time in a regular pattern. People can:

  • Stay awake all day
  • Sleep well and switch between non-REM sleep and REM sleep at night
Wakefulness infographic

A person is aware, alert, and can think clearly.

Non-REM Sleep infographic

Light sleep to deep restorative sleep, usually without dreaming.

REM Sleep

Dreams normally occur; most muscles are not active, so people do not act out their dreams.

What in the Brain Affects Sleep and Wakefulness?

Many chemicals in the brain, including hypocretin and histamine, play important roles in sleep and wakefulness, Hypocretin helps people stay awake and prevents non-REM sleep and REM sleep from happening during the day. Histamine plays a similar role in sleep and wakefulness. If the brain loses hypocretin, states of sleep and wakefulness can happen at the wrong time.

Sleep Icon

People living with narcolepsy may fall asleep during the day.

What Happens in People Living With Narcolepsy?

In most people living with narcolepsy, hypocretin levels are low—sometimes too low to be detected. With low or no hypocretin, people are more likely to have cataplexy and severe sleepiness.

Sleep Icon

People living with narcolepsy may fall asleep during the day.

In narcolepsy, the separate states of wakefulness and sleep do not work properly, shifting often from one state to another at the wrong time. People living with narcolepsy may:

  • Fall asleep during the day (excessive daytime sleepiness)
  • Wake up many times during the night (disrupted nighttime sleep)

The boundaries between sleep and wakefulness may also break down:

  • Some aspects of sleep can interrupt wakefulness
  • Some aspects of wakefulness can interrupt sleep
Cataplexy Graphic

Cataplexy happens when muscle weakness briefly interrupts wakefulness

Certain aspects of REM sleep, like the inability to move certain muscles, can happen briefly during wakefulness and lead to cataplexy.

Aspects of REM sleep can happen when a person is falling asleep or waking up.

  • During sleep paralysis, people are unable to move, like in REM sleep
  • Hypnagogic hallucinations are vivid dreamlike images, similar to the dreams that normally happen during REM sleep
Cataplexy Graphic

Cataplexy happens when muscle weakness briefly interrupts wakefulness

Narcolepsy assessment tool thumbnail

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Performance of routine tasks without awareness or memory.

Difficulty focusing or concentrating.

Brief loss of muscle tone with retained awareness, often triggered by strong emotions.

Frequent shifts between different states of sleep and wakefulness at night.

The inability to stay awake and alert during the day; a constant need for sleep or unintentionally falling asleep.

A chemical in the brain that helps maintain wakefulness.

Vivid dream-like experiences that occur while falling asleep.

Dream-like events that occur when falling asleep. Called hypnopompic hallucinations if they occur when waking up.

A chemical in the brain that helps maintain wakefulness and prevent non-REM sleep and REM sleep from occurring at the wrong time.

Unintentionally falling asleep due to excessive daytime sleepiness; “sleep attacks.”

Restorative sleep state with decreased muscle tone.

Occurs at night and includes dreams; muscles are not active to prevent people from acting out dreams.

Daytime and evening habits to improve sleep.

Brief total loss of voluntary muscle control when falling asleep or while waking up.

People with type 1 narcolepsy can be diagnosed by their cataplexy or low levels of hypocretin.

The cause of type 2 narcolepsy is unknown.