For many people, it is common to feel sleepy throughout the day, even when they’ve had a good night's sleep. Well, according to new research, this could be due to a sleep disorder that was previously believed to be quite rare.
Idiopathic hypersomnia is a neurological disorder that, among its symptoms, can cause people to feel very tired during the day, sleep for excessive periods of time, have difficulty waking up, and even wake up disorientated.
While similar in nature, this is different from the more common narcolepsy. Narcolepsy can also cause people to feel tired throughout the day, but usually, people suffering from it are not getting excessive sleep and can wake up feeling refreshed from naps.
“It has been difficult to determine the prevalence of idiopathic hypersomnia because expensive and time-consuming sleep testing is required to make a diagnosis,” said study author Dr David T Plante, from the University of Wisconsin–Madison.
“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.”
To examine the disorder, the researchers studied sleep data for 792 people with an average age of 59. Every participant had to complete an overnight sleep study, as well as a daytime nap study, measuring how fast someone falls asleep.
The participants were surveyed further on daytime sleepiness, fatigue, the amount of time napping, and how many hours of sleep they get on a worknight and non-worknight.
With the results of the tests, the researchers were able to determine that 12 people had probable cases of idiopathic hypersomnia. That means a prevalence of 1.5 per cent, with the participants in this bracket reporting more severe sleepiness, despite longer sleeping time.
In the surveys that measured sleepiness, a score range was set up between 0 and 24. Questions included how likely a person is to nod off while sitting, talking and while stopped in a car.
On average, people with idiopathic hypersomnia had a score of 14, while those without averaged nine. Anything over 10 was deemed concerning.
The researchers also addressed daytime sleepiness in people with idiopathic hypersomnia over an average of 12 years. They found for the 10 people where data was available, excess daytime sleepiness was often chronic. However, sleepiness went away for four people, or roughly 40 per cent of the group studied over a 12-year span.
“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,” said 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 only assessed employed people so the researchers note that rates of idiopathic hypersomnia could be even higher in the unemployed with higher rates of job loss and disability.
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