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What is IH?

Understanding your Idiopathic Hypersomnia (IH)

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Idiopathic Hypersomnia is a rare, lifelong sleep disorder.

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What does that mean?

Not many people know about Idiopathic Hypersomnia, which is why it is often mistaken for other conditions. Family, friends, and even doctors may need help understanding the symptoms and how it is different.

  • Idiopathic = The cause is unknown. Any disease or condition with an unknown source may be called idiopathic.
  • Hypersomnia = A condition that causes you to feel very sleepy during the day and/or makes you need excessive amounts of sleep.
  • Sleep disorder = There is a problem with the quality, timing, or amount of sleep.

An Idiopathic Hypersomnia diagnosis can be confirmed by identifying key symptoms and completing a sleep study (PSG/MSLT). Often, a doctor specializing in sleep medicine can help guide this process.

Idiopathic Hypersomnia is more than just feeling tired during the day.

It can include a range of symptoms.

Excessive Daytime Sleepiness

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Feeling very sleepy or tired during the day
  • Most common symptom of Idiopathic Hypersomnia

Sleep Inertia

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Severe grogginess or confusion when waking up regardless of how much sleep you get or how many alarms you set
  • Feeling disoriented, irritable, or even clumsy when waking up and for hours afterwards

Cognitive Impairment

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Difficulty focusing, trouble thinking clearly, or memory problems due to excessive daytime sleepiness
  • Often described as "brain fog"

Long Sleep Time

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Ability to sleep for many hours of the day
  • Sometimes for 11 hours or more

Non-Restorative Sleep

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Not feeling rested when waking up, despite sleeping a typical (or more than typical) amount each night

Long, Unrefreshing Naps

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Not feeling refreshed or better after napping (may even feel worse)
Patient William sharing how XYWAV® helped his Idiopathic Hypersomnia

Getting diagnosed with Idiopathic Hypersomnia was a wake-up call for me. I finally had a reason why it was so hard to get up and get going in the morning. I was sleeping so much, but it never felt like enough.”


XYWAV IH Ambassador

More on talking to your doctor about Idiopathic Hypersomnia

Real patient compensated for their time. Individual results may vary.

Idiopathic Hypersomnia Severity Scale (IHSS)

The IHSS was created by sleep experts to help determine the severity and frequency of symptoms in people with Idiopathic Hypersomnia and provide a measurement that may be useful for follow-up visits with a sleep specialist.

Use the IHSS to rate your symptoms on a 3- or 4-point scale for each question and review your responses with your doctor.

Download IHSS
Patient Jennie recalling her patient journey

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Diana, a real patient and XYWAV IH Ambassador, recalls her journey to an Idiopathic Hypersomnia diagnosis.

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other XYWAV IH Ambassadors

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XYWAV® (calcium, magnesium, potassium, and sodium oxybates) oral solution, 0.5 g/mL total salts (equivalent to 0.413 g/mL of oxybate) is a prescription medicine used to treat:

  • the following symptoms in people 7 years of age or older with narcolepsy:
    • sudden onset of weak or paralyzed muscles (cataplexy)
    • excessive daytime sleepiness (EDS)
  • idiopathic hypersomnia (IH) in adults.

Important Safety Information

WARNING: Taking XYWAV with other central nervous system (CNS) depressants such as medicines used to make you or your child fall asleep, including opioid analgesics, benzodiazepines, sedating antidepressants, antipsychotics, sedating anti-epileptic medicines, general anesthetics, muscle relaxants, alcohol, or street drugs, may cause serious medical problems, including trouble breathing (respiratory depression), low blood pressure (hypotension), changes in alertness (drowsiness), fainting (syncope), and death.

The active ingredient of XYWAV is a form of gamma-hydroxybutyrate (GHB). Abuse or misuse of illegal GHB alone or with other drugs that cause changes in alertness (or consciousness) has caused serious side effects. These effects include seizures, trouble breathing (respiratory depression), changes in alertness (drowsiness), coma, and death. Call your doctor right away if you or your child has any of these serious side effects.

Because of these risks, you have to go through the XYWAV and XYREM REMS to have your or your child's prescription for XYWAV filled.

Do not take XYWAV if you take or your child takes other sleep medicines or sedatives (medicines that cause sleepiness), drinks alcohol, or has a rare problem called succinic semialdehyde dehydrogenase deficiency.

Keep XYWAV in a safe place to prevent abuse and misuse. Selling or giving away XYWAV may harm others, and is against the law. Tell your doctor if you have ever abused or been dependent on alcohol, prescription medicines, or street drugs.

Anyone who takes XYWAV should not do anything that requires them to be fully awake or is dangerous, including driving a car, using heavy machinery, or flying an airplane, for at least 6 hours after taking XYWAV. Those activities should not be done until you know how XYWAV affects you or your child.

XYWAV can cause serious side effects, including the following:

  • Breathing problems, including slower breathing, trouble breathing, and/or short periods of not breathing while sleeping (sleep apnea). People who already have breathing or lung problems have a higher chance of having breathing problems when they use XYWAV.
  • Mental health problems, including confusion, seeing or hearing things that are not real (hallucinations), unusual or disturbing thoughts (abnormal thinking), feeling anxious or upset, depression, thoughts of killing yourself or trying to kill yourself, increased tiredness, feelings of guilt or worthlessness, or difficulty concentrating. Tell your doctor if you or your child have or had depression or have tried to harm yourself or themselves. Call your doctor right away if you have or your child has symptoms of mental health problems or a change in weight or appetite.
  • Sleepwalking. XYWAV can cause sleepwalking, which can cause injuries. Call your doctor if this occurs.

The most common side effects of XYWAV in adults include nausea, headache, dizziness, anxiety, insomnia, decreased appetite, excessive sweating (hyperhidrosis), vomiting, diarrhea, dry mouth, parasomnia (a sleep disorder that can include abnormal dreams, abnormal rapid eye movement (REM) sleep, sleep paralysis, sleep talking, sleep terror, sleep-related eating disorder, sleepwalking, and other abnormal sleep-related events), somnolence, fatigue, and tremor.

The most common side effects of XYREM (which also contains oxybate like XYWAV) in children include nausea, bedwetting, vomiting, headache, weight decrease, decreased appetite, dizziness, and sleepwalking.

XYWAV can cause physical dependence and craving for the medicine when it is not taken as directed. These are not all the possible side effects of XYWAV.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit, or call 1-800-FDA-1088.

Please see full Prescribing Information, including BOXED Warning, and Medication Guide.

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