People suffering from hypersomnolence, sleep an excessive amount of time at night, take long naps during the day, and generally feel drowsy and distracted when awake. This serious neurological sleep disorder can be permanent or temporary, yet it's often misdiagnosed. Hypersomnolence can be related to a genetic predisposition, caused by another health condition, or idiopathic, which means it has no known cause.

If you have hypersomnolence, you need far more sleep than normal people. You might sleep more than 10 hours every night, yet still require extended naps lasting longer than an hour throughout the day. Attempts at waking up, such as phone calls or alarms, are usually ineffective. Even with this much of your life spent sleeping, you won't feel refreshed or rested. Instead, your thinking and motor coordination might be bumbling, cloudy, or confused. If you exhibit these symptoms, make sure to get a proper diagnosis from your general physician or sleep expert.

When your body is recovering from an exhausting condition, like an infection, surgery, or mononucleosis, you can expect some degree of hypersomnolence as you fully heal. Other known causes include sleep apnea and periodic movement of your legs. During the night, those conditions create frequent disturbances in smooth, rejuvenating sleep without completely awaking you. Thus, during the day you may crave naps to make up for poor rest. A build-up of magnesium, a mineral some people take as a vitamin supplement, has been known to cause hypersomnolence. Depression has also been associated with daytime sluggishness.

Temporary hypersomnolence can usually be treated by addressing the underlying cause, such as sleep apnea or infection, until you can depend on a restful night of sleep. Periodic hypersomnolence, called Kleine-Levin syndrome, means you go through periods of normal sleep followed by excessive sleep. While it might be genetic, at this point doctors can only treat the symptoms by prescribing stimulants to keep you awake and alert during the day.

Hypersomnolence differs somewhat from other sleep disorders, such as insomnia or narcolepsy, yet people frequently confuse them. Insomnia, or the inability to sleep through the night, might create excessive exhaustion that in turn causes hypersomnolence. This variety could be only temporary. Narcolepsy is closely related to hypersomnolence in the sense that both make you fall asleep in the middle of the day. Narcoleptics experience REM sleep (which involves dreaming), whereas hypersomnolence sleep is non-REM sleep.