In all cases with these mood disorders, the MSLT is normal (not too short and no SOREMPs). Posttraumatic hypersomnias
In some cases, hypersomnia can be caused by a brain injury. Researchers found that the level of sleepiness is correlated with the severity of the injury. Even if patients reported an improvement, sleepiness remained present for a year in about a quarter of patients with traumatic brain injury. Recurrent hypersomnias
Recurrent hypersomnias are defined by several episodes of hypersomnia persisting from a few days to weeks. These episodes can occur weeks or months apart from each other. There are 2 subtypes of recurrent hypersomnias: Kleine-Levin syndrome and menstrual-related hypersomnia.Kleine-Levin syndrome is characterized by the association of episodes of hypersomnias with behavioral, cognitive and mood abnormalities. The behavioral disturbances can be composed of hyperphagia, irritability, or sexual disinhibition. The cognitive disorders consist of confusion, hallucinations or delusions. Mood symptoms are characterized by anxiety or depression.Menstrual-related hypersomnia is characterized by episodes of excessive sleepiness associated with the menstrual cycle. Researchers found that the degree of premenstrual symptoms were correlated with daytime sleepiness. Unlike Kleine-Levin syndrome, hyperphagia and hypersexuality are not reported in people with menstrual-related hypersomnia, but hypophagia could be present. Ordinarily, these episodes appear 2 weeks before menstruation. A few studies have attested that some hormones as prolactin and progesterone could be responsible for Menstrual-Related Hypersomnia. Therefore, different contraceptive pills could improve the symptoms. The sleep architecture changes. There is a decrease of slow-wave sleep and an increase of slow-Theta-wave activity. Assessment tools
Polysomnography
Polysomnography is an objective sleep assessment method.
It comprises a lot of electrodes which measure physiological variables related to sleep. Polysomnography often includes electroencephalography, electromyography, electrocardiography, muscle activity and respiratory function.Polysomnography is helpful to identify the very short sleep onset latency period, the very efficient sleep (more than 90%), the increased slow wave sleep, and sometimes an elevated amount of sleep spindles in idiopathic hypersomnia patients. Multiple sleep latency test (MSLT)
The multiple sleep latency test (MSLT) is an objective tool which indicates the degree of sleepiness by measuring the sleep latency (i.e. the speed of falling asleep). It also gives information regarding the presence of abnormal REM sleep onset episodes. During that test, patients have a series of opportunities to sleep at 2-h intervals across the day in a darkened room and with no external alerting influences.The MSLT is often administered the day after recording the polysomnography, and the mean sleep latency score is often found to be around (or less than) 8 minutes in idiopathic hypersomnia patients. Some patients might even have a sleep onset latency of 5 minutes or less. These patients are often even more aware of sleeping during naps than narcolepsy patients. Actigraphy
Actigraphy, which operates by analyzing the patients limb movements, is used to record the sleep and wake cycles. In order to report them, the patient has to wear continuously a device on his or her wrist, which looks like a watch and does not contain any electrodes. The advantage actigraphy shows over polysomnography is that it is possible to record for 24-hours a day for weeks.