Hypersomnia and Narcolepsy

Introduction to Hypersomnias

  • Hypersomnias are defined as excessive daytime sleepiness.

  • It can significantly affect daily life and functioning.

Overview of Central Disorders of Hypersomnolence

  • Hypersomnia vs. Hypersomnolence:

    • Hypersomnia: A specific disease state.

    • Hypersomnolence: Refers to symptoms characterized by prolonged sleep or excessive daytime sleepiness.

Primary and Secondary Hypersomnias

  • Primary Hypersomnias:

    • Narcolepsy Type 1

    • Narcolepsy Type 2

    • Idiopathic Hypersomnia

    • Kleine-Levin Syndrome

  • Secondary Hypersomnias:

    • Due to a medical condition

    • Due to medication or substance use

    • Associated with a psychiatric disorder

Narcolepsy

  • Definition: A chronic neurological sleep disorder affecting the sleep-wake cycle regulation.

  • Key Characteristics:

    • Excessive daytime sleepiness (EDS)

    • Unstable transitions between sleep and wakefulness

    • Abnormal REM sleep intrusions.

  • Onset: Typically starts in childhood, adolescence, or young adulthood.

Prevalence of Narcolepsy

  • Affects approximately 1 in 2,000 people in the U.S. and Western Europe.

  • Estimated around 3 million individuals worldwide.

  • Prevalence is higher in Japan at about 1 in 600 due to genetic susceptibility.

Diagnostic Criteria for Narcolepsy

Narcolepsy Type 1 (with Cataplexy)

  • Criteria A: Daily irrepressible need to sleep or daytime lapses into sleep for at least 3 months.

  • Criteria B: At least one of the following must be present:

    1. Cataplexy and mean sleep latency of ≤ 8 minutes with 2+ SOREMPs on multiple sleep latency test (MSLT).

    2. CSF orexin/hypocretin-1 concentration ≤ 110 pg/mL or < 1/3 of mean values.

Narcolepsy Type 2 (without Cataplexy)

  • Criteria A: Daily irrepressible need to sleep or daytime lapses into sleep for at least 3 months.

  • Criteria B: Mean sleep latency ≤ 8 min with 2+ SOREMPs.

  • Criteria C: Cataplexy is absent.

  • Criteria D: CSF orexin/hypocretin-1 concentration > 110 pg/mL.

  • Criteria E: Symptoms not explained by other causes.

Cataplexy

  • Defined as brief, sudden episodes of muscle weakness or paralysis often triggered by strong positive emotions.

  • Symptoms may range from mild (eyelid droop) to severe (total collapse).

  • Muscle groups affected include:

    • Eyelids

    • Jaw

    • Head

    • Grip

Symptoms of Narcolepsy

  • Excessive Daytime Sleepiness (EDS): The primary symptom causing drowsiness and sudden "sleep attacks".

  • Cataplexy: Sudden loss of muscle tone, affecting both sides of the body, episodes lasting seconds to minutes.

  • Automatic Behaviors: Continuing activities without awareness, such as writing nonsense.

  • Disrupted Nighttime Sleep: Leads to frequent awakenings and sleep fragmentation.

  • Sleep Paralysis: Temporary inability to move when falling asleep or waking up.

  • Sleep-Related Hallucinations: Vivid imagery occurring during sleep onset or waking; often frightening.

KLS (Kleine-Levin Syndrome)

  • Defined as a rare neurological disorder characterized by recurring episodes of excessive sleep, behavioral changes, and cognitive disturbances.

  • Described as “Sleeping Beauty Syndrome.”

  • Episodes are remitting-relapsing.

Diagnostic Criteria for KLS

  • Criteria A: At least two recurrent episodes of excessive sleep lasting 2 days to 5 weeks.

  • Criteria B: Episodes must recur more than once a year.

  • Criteria C: Normal alertness and function between episodes.

  • Criteria D: At least one of the following during episodes:

    1. Cognitive dysfunction

    2. Altered perception

    3. Eating disorder

    4. Disinhibited behavior

  • Criteria E: Symptoms are not better attributed to other disorders.

Epidemiology of KLS

  • Rare prevalence of 1-2 cases per million people.

  • Males affected more than females (2-3 males for every female).

  • Typically begins in adolescence with an average onset age of 15 years.

  • Risk factors include birth and developmental problems.

Idiopathic Hypersomnia

  • Defined as a rare central nervous system disorder characterized by excessive daytime sleepiness.

  • Symptoms include long, unrefreshing sleep and difficulty waking up, often with sleep inertia.

Diagnostic Criteria for Idiopathic Hypersomnia

  • Must meet specific criteria:

    1. Daily daytime sleepiness for at least 3 months.

    2. No cataplexy.

    3. No MSLT evidence for narcolepsy.

    4. Evidence of hypersomnolence via the MSLT or PSG.

    5. Insufficient sleep ruled out.

    6. No other disorder explaining the symptoms.

Epidemiology of Idiopathic Hypersomnia

  • Exact prevalence unknown but less common than narcolepsy.

  • Onset typically between 10 to 30 years.

  • Symptoms are usually stable and long-lasting.

  • Some studies suggest higher prevalence in females.

Treatment for Narcolepsy

  • Sleep Hygiene: Maintain consistent sleep schedule and conducive sleep environment.

  • Scheduled Naps: Short naps (10-30 minutes) to alleviate EDS.

  • Education and Support: Inform relevant personnel for accommodation.

  • Medications:

    • Stimulants such as Modafinil or Armodafinil as first-line treatment.

    • Sodium Oxybate used for managing cataplexy.