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Idiopathic hypersomnia is a sleep disorder without a clear cause, in which you are excessively sleepy (hypersomnia) during the day. It is different from narcolepsy, because idiopathic hypersomnia does not involve suddenly falling asleep or losing muscle control due to strong emotions (cataplexy).
Hypersomnia - idiopathic; Drowsiness - idiopathic; Somnolence - idiopathic
The usual approach is to consider other potential causes of excessive daytime sleepiness.
Other sleep disorders that may cause daytime sleepiness include:
Other causes of excessive sleepiness include:
Symptoms often develop slowly during adolescence or young adulthood. They include:
- Daytime naps that do not relieve drowsiness
- Difficulty waking from a long sleep -- may feel confused or disoriented
- Increased need for sleep during the day -- even while at work, or during a meal or conversation
- Increased sleep time -- up to 14 to 18 hours per day
Other symptoms may include:
- Feeling irritated
- Loss of appetite
- Low energy
- Slow thinking or speech
- Trouble remembering
Cataplexy -- suddenly falling asleep or losing muscle control -- which is part of narcolepsy, is not a symptom of idiopathic hypersomnia.
Exams and Tests
The health care provider will take a detailed sleep history. Tests may include:
- Multiple-sleep latency test
- Sleep study (polysomnography, to identify other sleep disorders)
A psychiatric evaluation for atypical depression may also be done.
Idiopathic hypersomnia is usually treated with stimulant medications such as amphetamine, methylphenidate, and modafinil. These medicines may not work as well for this condition as they do for narcolepsy.
If an underlying cause of the hypersomnia is found, it should be treated.
Lifestyle changes that can help ease symptoms and prevent injury include:
- Avoiding alcohol and medications that can make the condition worse
- Avoiding operating motor vehicles or using dangerous equipment
- Avoiding working at night or social activities that delay bedtime
Chokroverty S, Avidan AY. Sleep and its disorders. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC, eds. Bradley's Neurology in Clinical Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 68.
Masri TJ, Gonzales CG, Kushida CA. Idiopathic hypersomnia. Sleep Med Clin. 2012;7:283-289.
Reviewed By: Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.