Hypersomnia is the opposite of insomnia. People with hypersomnia sleep too much. Of course, "too much" is a subjective evaluation. You can always argue that the person "needs" that much sleep, and in reality, there is no fixed amount of sleep that's right for everyone.
But serious health professional try to define hypersomnia as a real medical phenomenon. It is an excessively deep or prolonged major sleep period – a time of 10 hours per night is thrown around, although there are no specific diagnostic criteria on length of sleep. Hypersomniacs do not find nighttime sleep refreshing either; they are still sleepy during the day. In addition to a long nighttime sleep period the hypersomniac naps during the day, often repeatedly. At its worst, these naps take place at socially awkward times, and they do not leave the hypersomnia feeling refreshed. Many people experience hypersomnia periodically with episodes occurring weeks or months apart.
"Even were sleep is concerned, too much is a bad thing" - Homer
Not only do hypersomniacs sleep for a long time, but they have trouble getting up and often experience sleep inertia. Polysomnograms show some hypersomniacs experience sleep-onset REM - that is, they enter into REM very early after going to bed, while normal people do not enter REM for several hours. Daytime symptoms that can be observed without fancy monitoring equipment include the person’s anxiety, irritability, and difficulty remembering things and doing cognitive takes. "Sleep drunkenness" is common. In really severe cases hallucinations can occur, although this is usually indicative of another co-morbid psychiatric problem. If it’s bad enough, the hypersomniac suffers problems in everyday life due to his or her condition.
The onset is insidious (gradually, so you are not aware of it at first). Hypersomnia typically affects adolescents and young adults and continues through life. It is very rare when the onset happens past age 40, except in case of brain injuries. There is some tendency for hypersomnia to run in families.
Kleine-Levin syndrome is a recurrent form of hypersomnia. It is also called recurrent hypersomnia. Some clinicians distinguish between Kleine-Levin syndrome with and without compulsive eating. There is also menstrual-related hypersomnia. Narcolepsy could also be classified as a form of hypersomnia.
Like insomnia, hypersomnia can have many causes. Head injuries often result in hypersomnia (also called hypersomnolence), as does drug or alcohol abuse. Brain tumors and other nervous system pathologies, including start of withdrawal of medicines (there is a lot of variation from person to person in reaction to medicines) may also cause hypersomnia. Post-traumatic stress disorder sometimes produces hypersomnia as a symptom. It is estimated that over 45% of hypersomnia patients have a co-morbid psychiatric condition.
People with Parkinson’s disease often have excessive daytime sleepiness (EDS) which is not the same as hypersomnia, However, specialists looking into this mysterious disease are finding clues that there may be a predilection for hypersomnia among Parkinson’s patients. Other forms of dementia may be associated with hypersomnia, although there is little evidence to say for sure at this time.
Types of hypersomnia include recurrent, post-traumatic, and idiopathic. When the cause is unknown the hypersomnia is called idiopathic hypersomnia. The International Classification of Sleep Disorders distinguishes between two types of idiopathic hypersomnia based on length of nighttime sleep: more than 10 hours continuously at night is called Idiopathic Hypersomnia with long sleep and a period between 6 and 10 hours is called Idiopathic Hypersomnia with short sleep. Although the nocturnal sleep time for those with short sleep is in the normal range, a diagnosis of hypersomnia may be given if the patient has a sleep latency of less than eight minutes, excessive daytime sleepiness, and unrefreshing daytime naps. Various sleep diagnostic techniques can get the numbers on sleep latency and excessive sleepiness during the day. If a head injury is suspected, imaging techniques like CT and MRI scans may be employed.
When patients are evaluated with the Multiple Sleep Latency Test, a finding of a sleep latency lasting less than eight minutes is support for a diagnosis of hypersomnia. The difference between hypersomnia and narcolepsy on the MSLT is that the narcoleptics will have two or more sleep-onset rapid eye movements. Hypersomniacs also tend to take longer daytime naps than narcoleptics, although neither experience much refreshment from daytime napping. People who suspect they have hypersomnia often overestimate the amount of time they spend sleeping; a sleep study is the best way to determine for sure if the condition is present. Even doctors have a hard time distinguishing between narcolepsy and hypersomnia without a polysomnogram.
People with idiopathic hypersomnia low levels of orexins in their cerebrospinal fluid. Scientists at Emory University concluded that there is something else in the spinal fluid of hypersomniacs, but they were unable to put their fingers on it.
Note that Excessive Daytime Sleepiness and hypersomnia are not the same thing. EDS is a symptom of many disorders and very common, sometimes clearing up when the subject starts getting good sleep again. Hypersomnia can exist even without EDS.
Treatment for idiopathic hypersomnia attacks the symptoms, not the underlying cause, because the underlying cause is unknown or no treatment for the causes exist. Doctors often prescribe stimulants just to keep people awake, including dexamphetamine, methylphenidate (Ritalin), Adderall, and modafinil (Nuvigil or Provigil). Other drugs used to treat hypersomnia include clonidine, amphetamine, levodopa, bromocriptine, antidepressants, and monoamine oxidase inhibitors. In recent years modafinil is growing in popularity because of its low side effects profile. Specialists also recommend working on sleep hygiene practices similar to those for other sleep disorders. (Good sleep hygiene is always recommended.) It may sound paradoxical, but the practices recommended for people with insomnia can sometimes help with hypersomnia.
The prognosis for persons with hypersomnia depends on the cause of the disorder. Idiopathic insomnia may disappear on its own after a period of years – this happens sometimes – but there is no expectation it will disappear as the cause of the hypersomnia is unknown. Kleine-Levin Syndrome usually disappears as the patient grows to adulthood. Brain injuries are notoriously impracticable and often effectively permanent. Hypersomnia from traumatic head injuries or even Parkinson’s is not expected to clear up either, but so much of brain functioning is not clear. The medical prognosis is usually that the hypersomnia will continue.
Hypersomnia is not life threatening, but in our modern society falling asleep at the wrong time can be dangerous. Further, EDS results in reduced quality of life. Some people develop depression because of EDS and some, especially kids, develop hyperactivity.
Long sleepers (people who sleep more than normal) have higher mortality rates than normal sleepers but it is almost impossible to draw general conclusions from this fact as there are many factors that may influence sleep time. The hypersomnia itself is not a cause of death.
Did Sleeping Beauty have hypersomnia?
"Like all other forms of pleasure, sleep may become a passion" – Jean-Anthelme Brillat-Savarian – The Pyschology of Taste, 1825