(© Prostock-studio - stock.adobe.com)
MINNEAPOLIS — If you feel constantly tired during the day, it could be a sign of a rare sleep disorder that’s more common than scientists previously believed. A team with the American Academy of Neurology believes that more people may unknowingly have idiopathic hypersomnia, a disorder characterized by excessive daytime sleepiness.
Idiopathic hypersomnia is a neurological condition that causes individuals to feel extremely sleepy during the day, even after a good night’s sleep. Symptoms include prolonged sleep periods, difficulty waking up, and disorientation upon waking. This condition differs from narcolepsy, where individuals also experience daytime sleepiness but typically do not sleep excessively and may feel refreshed after napping.
“It has been difficult to determine the prevalence of idiopathic hypersomnia because expensive and time-consuming sleep testing is required to make a diagnosis,” says study author Dr. David Plante, from the University of Wisconsin–Madison, in a media release. “We examined data from a large sleep study and found that this condition is much more common than previous estimates, and as prevalent as some other common neurologic and psychiatric conditions such as epilepsy, bipolar disorder and schizophrenia.”
The study involved 792 participants with an average age of 59, who underwent an overnight sleep study and a daytime nap study. The nap study measures how quickly a person falls asleep over several naps. Participants also provided information about their daytime sleepiness, fatigue, napping habits, and sleep duration on work and non-work nights.
Researchers found that 12 participants had probable cases of idiopathic hypersomnia, representing a prevalence of 1.5 percent. Those with the disorder showed more severe sleepiness despite similar or longer sleep durations compared to those without the condition. On a sleepiness survey where scores above 10 are cause for concern, individuals with idiopathic hypersomnia averaged a score of 14, while others averaged a score of nine.
Sleep studies revealed that those with idiopathic hypersomnia fell asleep in about four minutes at night and six minutes during naps, in contrast to averages of 13 and 12 minutes, respectively, for those without the disorder. Over an average of 12 years, researchers observed that excessive daytime sleepiness was often a chronic issue for individuals with idiopathic hypersomnia. However, 40 percent of the studied individuals experienced a remission of sleepiness.
“Our results demonstrate that idiopathic hypersomnia is relatively common, more prevalent than generally assumed, so there is likely a sizable difference between the number of people with this disorder and those who seek treatment,” notes Dr. Plante. “Further efforts to identify, diagnose and treat those impaired by idiopathic hypersomnia are needed. Additional research may also clarify the causes of idiopathic hypersomnia and lead to new treatments.”
The study authors acknowledge some limitations of their work, including that participants were all employed, which might affect the outcomes. The condition could be even more prevalent in unemployed populations, as those with idiopathic hypersomnia have higher rates of job loss and disability.
Funding for the study was provided by Jazz Pharmaceuticals, which manufactures a treatment for idiopathic hypersomnia, along with the National Heart, Lung, and Blood Institute and the National Center for Research Resources at the National Institutes of Health. Plante has served as a consultant for Jazz Pharmaceuticals. The study asserts that funders did not influence the research process or findings.
The study is published in the journal Neurology.
