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Idiopathic Hypersomnia

Last updated May 30, 2018

Approved by: Krish Tangella MD, MBA, FCAP

Idiopathic Hypersomnia is a very uncommon disorder. The signs and symptoms begin slowly. In some individuals, the symptoms may either gradually worsen over a period of time, or the symptoms may get better with time.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Idiopathic Drowsiness
  • Idiopathic Somnolence
  • Primary Hypersomnia

What is Idiopathic Hypersomnia? (Definition/Background Information)

  • Hypersomnia means excessive sleepiness, and in this condition, even after taking long naps the individual does not feel rested
  • There are two types of hypersomnia:
    • Primary Hypersomnia (also called Idiopathic Hypersomnia): In Primary Hypersomnia, the excessive sleepiness happens over a period of many months or sometimes, even for many years. The excessive sleepiness occurs without periods of normality
    • Recurrent hypersomnia (also called primary recurrent hypersomnia): In recurrent type of hypersomnia, the symptoms last for many years, but the individual is symptom- free for a period of time (that can last for months) between episodes of hypersomnia. This normal sleep period between periods of excessive sleep is very characteristic of Kleine-Levin syndrome
  • Excessive sleep occurs during the day which is called excessive daytime sleepiness. Due to excessive daytime sleepiness, the individual is forced to take naps during the day, which interrupts their daily routine. Moreover, frequent naps during the day do not refresh the individual
  • Idiopathic Hypersomnia is a very uncommon disorder. The signs and symptoms begin slowly. In some individuals, the symptoms may either gradually worsen over a period of time, or the symptoms may get better with time
  • The outcome of Idiopathic Hypersomnia is dependent upon the severity of the disorder

Who gets Idiopathic Hypersomnia? (Age and Sex Distribution)

  • The signs and symptoms of Idiopathic Hypersomnia usually start during teenage or around young adulthood
  • Both males and females are affected by Idiopathic Hypersomnia

What are the Risk Factors for Idiopathic Hypersomnia? (Predisposing Factors)

The risk factors associated with Idiopathic Hypersomnia are:

  • Family history of the disorder
  • Severe brain damage such as due to a trauma
  • Severe depression 
  • Fibromyalgia 
  • Liver failure, kidney failure
  • Celiac disease 
  • Restless leg syndrome 
  • Bipolar disorder
  • Sleep apnea
  • Narcolepsy
  • Infectious mononucleosis
  • Thyroid disorders
  • Excessive weight

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Idiopathic Hypersomnia? (Etiology)

The exact cause of Idiopathic Hypersomnia, a sleep disorder, is unknown.

  • It has been postulated that the cause may be due to brain dysfunction in chemical substances
  • In the brain there are substances called neurotransmitters. Normal brain activity occurs due to a fine balance between many different types of neurotransmitters
  • Sometimes, there is an imbalance of neurotransmitters in the brain. In Idiopathic Hypersomnia there is hyperactivity of a receptor called GABA receptors

What are the Signs and Symptoms of Idiopathic Hypersomnia?

The signs and symptoms of Idiopathic Hypersomnia include:

  • Difficulty in sleeping at night, difficulty waking up from a long sleep
  • Not feeling rested after a sleep
  • Increased stress and anxiety 
  • Lack of appetite
  • Poor work performance
  • Memory problems
  • Slurred speech

Sometimes, after waking up from a long sleep, the individual feels irritable and disoriented. This is called sleep drunkenness.

How is Idiopathic Hypersomnia Diagnosed?

Idiopathic Hypersomnia is a diagnosis of exclusion. The diagnosis is usually arrived at after a thorough medical examination for possible causes of hypersomnia. A diagnosis of Idiopathic Hypersomnia is made if an individual has excessive sleep for a period of more than a month that significantly affects the quality of life.

  • A good clinical history is very important and helps in arriving at an accurate diagnosis of Idiopathic Hypersomnia
  • Possible causes for the symptoms, such as medications and other medical conditions causing excessive sleep, should be ruled out
  • Conditions resulting in excessive sleep may include:
    • Menstrual-related hypersomnia
    • Viral infection such infectious mononucleosis and atypical viral pneumonia
  • Blood tests to check for kidney and liver failure
  • A sleep study may help with the diagnosis
  • CT scan of head and MRI of the brain to rule out any brain damage

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Idiopathic Hypersomnia?

The possible complication of Idiopathic Hypersomnia includes severe damage to the quality of life. In children, it can lead to hyperactivity disorder.

How is Idiopathic Hypersomnia Treated?

There is no definitive treatment for Idiopathic Hypersomnia.

  • The healthcare professionals may treat the symptoms arising from the disorder
  • Sometimes, medication to keep the individual alert may be prescribed
  • Staying away from caffeinated drinks and alcoholic beverages help in decreasing the symptoms

How can Idiopathic Hypersomnia be Prevented?

Currently, there are no known measures to prevent Idiopathic Hypersomnia, since the exact cause of the condition is unknown.

What is the Prognosis of Idiopathic Hypersomnia? (Outcomes/Resolutions)

  • The prognosis of Idiopathic Hypersomnia depends upon the severity of the symptoms. The prognosis is excellent in individuals who have mild symptoms
  • On the other hand, for individuals with severe symptoms, the prognosis is guarded

Additional and Relevant Useful Information for Idiopathic Hypersomnia:

The following DoveMed website link is a useful resource for additional information:


What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 27, 2015
Last updated: May 30, 2018