Several people have written me because they have been diagnosed with idiopathic hypersomnolence. They are worried because they have no idea what the term means and their doctor hasn't given them an adequate explanation.
The truth is these are two big words with a very simple definition. Hypersomnolence is an excessive need for sleep, especially during the day. Idiopathic means without known cause. Put them together, and idiopathic hypersomnolence means a need for excessive daytime sleep without a known cause.
This condition can persist for long periods of time and make daily activities difficult if not impossible. The condition is similar to narcolepsy or even long periods of sleep deprivation. However, the difference is that, with other conditions, a few hours sleep will leave you feeling refreshed. Not so with idiopathic hypersomnolence. You awaken from your nap and a few minutes later you're as sleepy as you were before the nap.
People with this disorder suffer, not only from excessive daytime sleepiness, they also tend to oversleep at night as well, and still they remain sleepy. One sign that can be detected by the use of an EEG during sleep is numerous periods of non-REM sleep. The disorder is, in fact, occasionally referred to as non-REM narcolepsy.
The cause, as I've stated, is unknown although it may be linked to various viral infections. Viral pneumonia or mononucleosis is often sited as the cause. Guillain-Barré syndrome is also a possible cause. But, in many cases, the cause truly remains unknown.
Idiopathic Somnolence can be mistaken for other sleep disorders including narcolepsy and insomnia. Kleine Levin Syndrome, a rare disorder occasionally seen in teenagers, can produce similar symptoms. Even long stretches of sleep deprivation can cause excessive daytime sleepiness as can sleep apnea. If you think you may be suffering from idiopathic hypersomnolence, or that you may have been misdiagnosed with another disorder, ask for a sleep study or talk to a sleep specialist. Tests can often detect this disorder and there are drugs available to help combat the excess sleepiness and make life bearable again.
