Pulmonary, Sleep, and Critical Care Medicine
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Hypersomnias are disorders that involve excessive sleep and difficulty in staying awake during the day. The core symptom is excessive daytime sleepiness that is not due to other identifiable causes. Persistent sleepiness lasting more than three months without abnormalities specifically related to REM sleep is called idiopathic hypersomnia. A pattern of periodic isolated episodes of sleepiness is called recurrent hypersomnia.

Idiopathic Hypersomnia

Persons with idiopathic hypersomnia sleep far more than normal, have difficulty waking up, and feel tired, sleepy, or groggy during the day, and experience these symptoms more or less continuously for three months or more with a resulting significant impact on daily life. A diagnosis of idiopathic hypersomnia requires exclusion of other causes of daytime sleepiness such as insufficient sleep, disturbed nocturnal sleep, insomnia, circadian rhythm disorder, sleep-related breathing disorders, or medical issues.

Idiopathic hypersomnia can have many causes including brain abnormalities, low-grade infections, or a brain imbalance associated with psychiatric conditions. The disorder may arise from an abnormal sleep schedule, or sedative or stimulant medications taken in excess or at the wrong time.

Recurrent Hypersomnia

Recurrent hypersomnia is characterized by recurrent, reversible episodes of hypersomnia, often associated with other symptoms, that typically occur weeks or months apart. During the episodes the sufferers experience extreme sleepiness and have big sleep requirements, sometimes as much as 16 to 20 hours a day.