Idiopathic Hypersomnia

Diagnosis

It's important to exclude other disorders that can sometimes be mistaken for idiopathic hypersomnia. This typically involves conducting a physical exam, tracking a patient's sleep-wake patterns at home, and performing an overnight study (a polysomnogram — see below) at the sleep center followed by more testing the next day. Tests may include:

• Epworth sleepiness questionnaire: Gauge of tiredness and effects on daily life.
• Actigraphy: Tracking of sleep-wake cycles in the home environment with a small device worn like a wristwatch.
• Sleep diary: Daily sleep and wake time log — used in conjunction with actigraphy.
• Polysomnogram: A painless test in which sensors applied to the skin's surface record brain wave activity, eye movements, breathing function, oxygen levels, heart rate and muscle activity during sleep. This test is used to rule out other sleep disorders that can cause excessive daytime sleepiness, such as obstructive sleep apnea or periodic limb movement disorder.
• Multiple sleep latency test (MSLT): Test in which the patient is observed while taking naps throughout the day. Measures the time it takes a patient to fall asleep and to enter into rapid eye movement (REM) sleep. Patients with idiopathic hypersomnia fall asleep quickly, but don't tend to immediately enter REM sleep as often as patients with narcolepsy do. Early onset REM sleep during an MSLT is referred to as SOREMP (sleep onset rapid eye movement periods). This test is conducted the day after a polysomnogram.

Because some drugs can interfere with sleep center tests, patients may need to stop taking certain medications leading up to and during sleep studies.

Blood tests and psychological tests may also be needed to rule out underlying causes for excessive sleep.