Updated: Apr 15
Update in this research below.
Idiopathic hypersomnia (IH) is a poorly understood disorder, characterised by excessive sleep and daytime sleepiness. It has a severe impact on quality of life. An article published in the Sleep Research Society’s journal, SLEEP reports the first neuroimaging study of Idiopathic Hypersomnia, showing altered brain perfusion in regions modulating sleep-wake states. “These preliminary findings suggest that idiopathic hypersomnia is characterized by functional alterations in brain areas involved in the modulation of vigilance states, which may contribute to the daytime symptoms of this condition. The distribution of regional cerebral blood flow changes was reminiscent of the patterns associated with normal non-rapid-eye-movement sleep, suggesting the possible presence of incomplete sleep-wake transitions. These abnormalities were strikingly distinct from those induced by acute sleep deprivation, suggesting that the patterns seen here might reflect a trait associated with idiopathic hypersomnia rather than a non-specific state of sleepiness.”
This means that the daytime symptoms experienced by people with Idiopathic Hypersomnia are thought to be caused by incomplete transitions from NREM (Non-rapid eye movement) sleep to wakefulness (ie: people with IH don’t wake up completely), as opposed to what has been identified in people with narcolepsy with cataplexy and those that have insufficient sleep (ie: people who are sleep deprived). This study is significant because it could provide a trait that is specific to idiopathic hypersomnia that is not seen in others (particularly in those who have poor or insufficient sleep). *Words and link were originally shared by Hypersomnolence Australia when the study was published in October 2017. Follow up work on this study was published in the journal SLEEP on 21 October 2019 Beyond sleepy: structural and functional changes of the default-mode network in idiopathic hypersomnia. The researchers concluded that there was no visible change in the anatomy (structure) of the brain, but that some regions of the DMN were thicker and larger in people with Idiopathic Hypersomnia. Their findings suggest that, in people with Idiopathic Hypersomnia, there are important regions of the brain that are less able to communicate with each other during wakefulness, which might contribute to excessive daytime sleepiness and cognitive dysfunction. The researchers also suggested that the increase in the size of certain brain regions in people with Idiopathic Hypersomnia might result from the attempts of the brain to compensate for those deficits in brain function.