Hypersomnia

Hypersomnia, also known as hypersomnolence, is a neurological disorder characterised by excessive time spent sleeping or excessive sleepiness. It can lead to significant distress and impairment in daily functioning. This condition is often confused with fatigue, but it is primarily marked by a lack of alertness during waking hours.

Signs & Symptoms

The primary symptom of hypersomnia is excessive daytime sleepiness (EDS) or prolonged nighttime sleep, persisting for at least three months prior to diagnosis. Sleep drunkenness, or difficulty transitioning from sleep to wake, is also common. This includes waking with confusion, disorientation, slowness, and repeated returns to sleep. Other symptoms include irritability and unrefreshing long naps during the day.

Diagnosis

The diagnosis of hypersomnia involves a detailed assessment using subjective scales and objective tests. The Epworth Sleepiness Scale (ESS) and the Stanford Sleepiness Scale (SSS) are frequently used subjective measurements. Objective tests include:

• Polysomnography: Measures sleep-related physiological variables.
• Multiple Sleep Latency Test (MSLT): Measures sleep latency and the presence of abnormal REM sleep onset.
• Actigraphy: Records sleep and wake cycles over extended periods.
• Maintenance of Wakefulness Test (MWT): Assesses the ability to stay awake.

Differential Diagnosis

Differentiating hypersomnia involves identifying whether it is primary (central/brain origin) or secondary to other medical conditions. Primary hypersomnias include narcolepsy, idiopathic hypersomnia, and recurrent hypersomnias like Kleine-Levin syndrome.

Secondary hypersomnias can arise from conditions such as clinical depression, multiple sclerosis, epilepsy, obesity, and sleep disorders like sleep apnoea. Additionally, hypersomnia may result from medication side effects, substance use, genetic predispositions, head trauma, and other neurological disorders.

Primary Hypersomnias

Primary hypersomnias include narcolepsy (with or without cataplexy), idiopathic hypersomnia, and recurrent hypersomnias such as Kleine-Levin syndrome. Genetic disorders like Prader-Willi syndrome and neurodegenerative conditions such as Alzheimer's disease can mimic these primary hypersomnias.

Secondary Hypersomnias

Secondary hypersomnias are numerous and can be caused by various factors, including:

• Sleep Disorders: Sleep apnoea, restless legs syndrome (RLS), and periodic limb movement disorder (PLMD).
• Medical Conditions: Clinical depression, multiple sclerosis, epilepsy, obesity, and chronic kidney disease.
• Medications and Substance Use: Side effects or withdrawal from certain medications, substance use.
• Genetic and Neurological Disorders: Genetic predispositions, head trauma, and neurodegenerative conditions.

Assessment Tools

• Polysomnography: Identifies sleep onset latency, sleep efficiency, and other sleep characteristics.
• Multiple Sleep Latency Test (MSLT): Measures sleep latency and REM sleep onset.
• Actigraphy: Provides long-term monitoring of sleep-wake cycles.
• Maintenance of Wakefulness Test (MWT): Assesses the ability to stay awake.
• Stanford Sleepiness Scale (SSS): Subjective measurement of sleepiness levels.
• Epworth Sleepiness Scale (ESS): Measures general daytime sleepiness.

Treatment

There is no definitive cure for chronic hypersomnia, but various treatments can improve patients' quality of life. Behavioural treatments and sleep hygiene practices are recommended. Pharmacological treatments include modafinil, which is effective in managing excessive sleepiness. Patients are advised to use their bed only for sleep or sexual activity and to go to bed only when feeling sleepy.

Epidemiology

Hypersomnia affects approximately 5% to 10% of the general population, with a higher prevalence in men due to sleep apnoea syndromes.

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Self-assessment MCQs (single best answer)

What is the primary symptom of hypersomnia?

Which subjective measurement is commonly used to assess daytime sleepiness in hypersomnia?

What does the Multiple Sleep Latency Test (MSLT) measure?

Which of the following is NOT a primary hypersomnia?

What device is used to record sleep and wake cycles over long periods?

Which medication is most effective in managing excessive sleepiness in hypersomnia patients?

What is sleep drunkenness?

Which of the following is a secondary cause of hypersomnia?

What is the purpose of the Maintenance of Wakefulness Test (MWT)?

Which population has a higher prevalence of hypersomnia due to sleep apnoea syndromes?