Idiopathic Hypersomnia (IH), sometimes referred to as Idiopathic Hypersomnolence, is a neurological sleep/wake disorder characterised by excessive sleep, chronic daytime sleepiness and cognitive dysfunction. It is a debilitating condition often profoundly affecting work, education and relationships.  Idiopathic Hypersomnia is quite rare and the cause is poorly understood.

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Most people can feel tired, fatigued and at times, excessively sleepy, particularly when they do not get enough sleep. However what sets people with IH apart, is that they experience extreme sleepiness despite getting adequate, or typically more than adequate, hours of sleep. Their sleep may be deep and uninterrupted, but it is not refreshing. Despite extraordinary amounts of good quality sleep people with IH are in an almost constant state of sleepiness.

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Symptoms
The main symptoms of IH is excessive deep sleep and excessive daytime sleepiness. Despite adequate and often extraordinary amounts of good quality sleep (eg: 11 hours or more per night) people with IH still feel excessively sleepy during the day. Other symptoms typically include:

• Chronic excessive daytime sleepiness often resulting in long daytime naps.

• Long and unrefreshing naps. Naps are usually more than one hour long and are typically not refreshing

• Extreme and prolonged difficulty awakening from sleep, confusion, disorientation, irritability and poor coordination, with an uncontrollable desire to go back to sleep. It can also be accompanied by automatic behaviour (performing tasks without consciously knowing it and not remembering you have done them eg: turning off alarm clocks or answering your phone). This is clinically known as “sleep drunkenness”.

• Cognitive dysfunction (commonly referred to as 'brain fog'): problems with memory, automatic behaviour, concentration and attention. Unlike in other sleep disorders, the sleep in patients with Idiopathic Hypersomnia is normal; there are no disturbances that can account for these symptoms.
  
  Unlike in other sleep disorders, the sleep in patients with Idiopathic Hypersomnia is normal; there are no disturbances that can account for these symptoms.

 

Diagnosis
Diagnosing IH can be difficult as excessive daytime sleepiness can be caused by various disorders and/or conditions as well as numerous medications. A physical examination, medical tests, and a comprehensive medical history are necessary to rule out all other possible causes, including insufficient sleep. Sleep studies involving a Polysomnography (PSG) followed immediately by a Multiple Sleep Latency Test (MSLT) are also carried out to exclude other sleep disorders such as sleep apnea.

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Treatment and Management
There are no medications specifically for Idiopathic Hypersomnia. Medications used to treat Narcolepsy, including stimulants and wake-promoting medications, are prescribed to counter the daytime sleepiness, however there are no medications currently available that assist with cognitive dysfunction or extreme difficulty waking up and sleep drunkenness. Stimulant and wake-promoting medications can be helpful to relieve sleepiness for some patients, however they are rarely effective long term. Some people with IH find a combination of medication and lifestyle changes are helpful in managing their symptoms. Lifestyles changes can be difficult to initiate (and maintain) for people with chronic illness and may need the assistance of a specialist therapist.

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Who does IH affect?
The pathogenesis of IH is unknown. An autosomal dominant mode of inheritance has been considered by researchers because around 50% of people with IH have at least one family member who also has symptoms. It appears IH may be more common in females. The prevalence of IH is thought to be 0.005%–0.3% but, due to lack of epidemiological studies, biological markers and misdiagnosis of the disease, the real prevalence is unclear.

Though the symptoms mainly begin in adolescence or young adulthood (typically between 15-30 years of age), it is not uncommon for there to be a delay of many years before an accurate diagnosis is made.
 

More information can be found at Hypersomnolence Australia

Click here for information on the worldwide Idiopathic Hypersomnia Awareness Week® and for awareness posters you can share on social media.