Hypersomnia

Idiopathic hypersomnia is a chronic condition that results in excessive daytime sleepiness, often combined with long yet non-restorative naps. Despite good-quality – and often prolonged – night-time sleep, the subject has great difficulty waking up in the morning, feels confused and groggy, and can even fall back to sleep. This is called confusional arousal or « sleep drunkenness ». This condition is extremely rare and generally occurs between the ages of 16 and 21. Unlike narcolepsy, IH is characterised by the absence of cataplexy.

Narcolepsy is a rare sleep disorder that can occur from childhood. It is characterised by severe daytime sleepiness despite regular night sleep. A narcoleptic patient feels the irrepressible need to sleep at any time of the day, even in unusual situations. Some subjects also experience cataplexy, i.e. an abrupt loss of muscle tone, either total or partial, triggered by – usually positive – emotions. These episodes are quite brief, but can be spectacular. Furthermore, subjects may experience hallucinations and/or sleep paralysis when falling asleep or waking up.

Kleine-Levin syndrome (KLS) is a very rare disease. It occurs most often during adolescence, and affects men more than women. The syndrome is characterised by recurring episodes of daytime sleepiness that can last from a few days to several weeks. Between these episodes, sleep duration returns to normal and daytime sleepiness disappears. KLS is also characterised by cognitive, psychiatric and behavioural disorders. In most cases, subjects experience other symptoms such as apathy, confusion and derealisation (altered perception of reality). In other, less frequent cases, subjects can suffer from eating disorders, hypersexuality, depression, anxiety and hallucinations. In the long term, episodes of hypersomnia tend to become less frequent and sometimes disappear with age.