“There was constant exhaustion. It didn't matter how much I slept.” – Scott

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Normal Sleep-Wake States

Optimal health and cognitive function require the coordinated timing and stability of three distinct states: wakefulness, non-REM sleep, and REM sleep.1-5

H11 Wakefulness

Normally, wakefulness is promoted during the day by multiple interconnected neuronal systems, including acetylcholine, dopamine, histamine, norepinephrine, and serotonin neurons.1,2 Wakefulness is characterized by high muscle tone and fast-frequency neuronal activity that is necessary for alertness and higher-order neurocognitive functioning. 3,5 Learn more »

H11 Non Rem Sleep

Non-REM sleep is a sleep state with slower-frequency neuronal activity and light to deep stages of non-REM sleep.3,5 Skeletal muscle tone is lower than during wakefulness.3,5 Nighttime sleep normally begins with an episode of non-REM sleep.3

H11 Rem Sleep

During REM sleep, which is associated with dreaming and skeletal muscle atonia, neuronal activity is faster and desynchronized, with distinct wave patterns (e.g., sawtooth waves) on electroencephalogram (EEG).3,5,7 Episodes of REM sleep typically occur at night after non-REM sleep and become longer over the course of the night.3

Normal Sleep-Wake Cycle

A normal sleep-wake cycle is generally characterized by consolidated wakefulness during the day and predictable, alternating periods of non-REM and REM sleep at night, generally with infrequent awakenings.2,3,7

Hypnogram Normal Infographic
Hypothalamus Brain Icon

The hypothalamus is a critical “control center” for sleep-wake state stability.

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Molecule Icon

In most patients, narcolepsy is caused by loss of hypocretin.

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  1. España RA, Scammell TE. Sleep neurobiology from a clinical perspective. Sleep. 2011;34(7):845-858.
  2. Scammell TE. The neurobiology, diagnosis, and treatment of narcolepsy. Ann Neurol. 2003;53(2):154-166.
  3. Scammell TE, Arrigoni E, Lipton JO. Neural circuitry of wakefulness and sleep. Neuron. 2017;93(4):747-765.
  4. Schwartz JR, Roth T. Neurophysiology of sleep and wakefulness: basic science and clinical implications. Curr Neuropharmacol. 2008;6(4):367-378.
  5. Brown RE, Basheer R, McKenna JT, Strecker RE, McCarley RW. Control of sleep and wakefulness. Physiol Rev. 2012;92(3):1087-1187.
  6. Broughton R, Valley V, Aguirre M, Roberts J, Suwalski W, Dunham W. Excessive daytime sleepiness and the pathophysiology of narcolepsy-cataplexy: a laboratory perspective. Sleep. 1986;9:205-215.
  7. Plazzi G, Serra L, Ferri R. Nocturnal aspects of narcolepsy with cataplexy. Sleep Med Rev. 2008;12(2):109-128.

Performance of routine tasks without awareness.

Sudden and brief loss of muscle strength or tone, often triggered by strong emotions. Narcolepsy with cataplexy is known as type 1 narcolepsy.

Complete collapse to the ground; all skeletal muscles are involved.

Only certain muscle groups are involved.

Biological clock mechanism that regulates the 24-hour cycle in the physiological processes of living beings. It is controlled in part by the SCN in the hypothalamus and is affected by the daily light-dark cycle.

Frequent inappropriate transitions between states of sleep and wakefulness.

The inability to stay awake and alert during the day.

A neurotransmitter that supports wakefulness. The TMN is the only source of histamine in the brain.

Vivid, realistic, and frightening dream-like events that occur when falling asleep.

Vivid, realistic, and frightening dream-like events that occur when falling asleep.

A neuropeptide that supports wakefulness and helps control non-REM sleep and REM sleep.

Primary brain region for regulating the timing of sleep-wake states.

Unintentionally falling asleep due to excessive daytime sleepiness.

Brief, unintentional lapses into sleep or loss of awareness.

A validated objective measure of the tendency to fall asleep in quiet situations.

A state of sleep when muscle tone is decreased. Deep stages help to restore the body.

Overnight study used to diagnose sleep disorders by monitoring sleep stages and cycles to detect disruptions of a normal sleep pattern.

Normally occurs at night and includes vivid dreams. Also known as “paradoxical sleep.”

Daytime and evening habits and routines to help improve nighttime sleep.

Brief loss of control of voluntary muscles with retained awareness at sleep-wake transitions.

Sleep-onset REM period.

People with type 1 narcolepsy have low levels of hypocretin.

Narcolepsy without cataplexy; the cause of type 2 narcolepsy is unknown.