Previewing Advancements in Hypersomnia Diagnosis and Treatment

On October 9, 2026, Northwestern Medicine will host its 4th Annual Updates in Neurology CME Symposium, a one-day course discussing the full range of neurological conditions. Designed for busy practitioners, the in-person symposium offers a concise but comprehensive look at the latest research, treatment methods, and evaluation strategies across neurology. The day-long program spans 10 sessions covering topics from movement disorders and headache medicine to ALS, concussion, autoimmune-associated seizure disorders, Alzheimer disease, multiple sclerosis, neuro-ophthalmic conditions, and neuroimaging.

Among the symposium's featured sessions is "Hypersomnia Overview and a Review of Therapies Old and New," presented by KuangHua Guo, MD, PhD, a sleep specialist at Northwestern Medicine. Guo's talk will walk attendees through the primary hypersomnias, with an emphasis on ruling out secondary causes like sleep apnea or heart failure before pursuing specialized sleep testing. He'll also spotlight the emerging class of orexin agonist medications, including Takeda's recently FDA-approved agent, which early phase 3 data suggest can meaningfully outperform older stimulant- and GABAergic-based treatments.

Ahead of his session at the symposium, Guo sat down with NeurologyLive® to preview what clinicians can expect from his talk on hypersomnia diagnosis and treatment. In the conversation, Guo discussed the wave of new orexin agonist therapies reshaping the hypersomnia treatment landscape. He also talked about how objective sleep testing can help distinguish tricky-to-differentiate conditions like idiopathic hypersomnia and narcolepsy type 2. In addition, he shared the practical takeaways he hopes general neurologists and advanced practice providers bring back to their own clinics after attending his session.

NeurologyLive: Of all the developments in hypersomnia treatment over the past several years, what would you highlight as the most significant shift clinicians should be aware of heading into your session?

KuangHua Guo, MD, PhD: I think hypersomnia has become one of the most exciting, cutting-edge parts of sleep medicine in general, mainly because of some big advancements in the medication field for treating hypersomnia. For a long time, we were treating hypersomnia with stimulants and/or a GABAergic agent to make patients sleep more fully and improve their arousal during the day, but we weren't really targeting the actual pathophysiology underlying hypersomnias like narcolepsy. Now there are a few different agents, which are basically orexin agonists, coming out from Takeda and Alkermes. Specifically, the Takeda one has just finished its phase 3 trials the FirstLight and RadiantLight trials, and has shown some promising data. So, I’m really excited to talk about the data and share that with everyone during my talk.

How do newer options compare with established stimulant-based regimens in terms of where each fits in a treatment algorithm?

I think we'll probably see a big shift in the first-line agents that we use to treat patients in the future as these new medications come out. Specifically, the ones I'm talking about are oveporexton or Orzeyful, the medication from Takeda that just got FDA-approved in August this year. Then Alkermes has a medication that's still undergoing phase 2 and will eventually go into phase 3. But what's exciting is that I think these medications show really good results compared with the prior medications.

If you look in the past, the most used medications for different types of hypersomnia, like narcolepsy or idiopathic hypersomnia, are things like modafinil and pitolisant. These are wake-promoting agents that don't really target the pathophysiology of the disease but keep you awake during the day. We also have sodium oxybate, which helps you fall asleep quicker and have more restful sleep, so that you're more awake during the day, hopefully. If you look at the data for those, the amount of wakefulness improvement is only about 3 to 4 minutes. By that, I mean the way we test how much we improve their wakefulness is by doing wakefulness maintenance testing, where we have them sit in a dark, quiet room and try not to fall asleep.

A healthy person can stay awake for 20 minutes, at least, or the whole time. But a lot of patients with narcolepsy or hypersomnia will fall asleep in less than 8 minutes. What we see with the older medications, like modafinil, for example, is that they only improve the amount of time you stay awake by about 4 minutes on average. But if you look at these new medications, the orexin agonists, like oveporexton, they improve wakefulness by about 20 minutes almost. So, it can basically make people normal, 14 to 20 minutes, depending on the dosage. It's really promising, the data so far, for how well they work.

Similarly, it really improves the Epworth Sleepiness Scale, which measures how likely you are to fall asleep in different situations during the day. Most of the older drugs improve this by maybe 1 to 3 points on average, and oveporexton has been shown to improve the ESS, or sleepiness scale, by about 8 to 9 points on average. Overall, the data seems really promising, and it also improves cataplexy symptoms in narcolepsy by about 80%.

I will say there are some adverse effects. Almost all the patients taking the medication have experienced some transient insomnia symptoms. That hasn't been studied long term, to see how long-lasting these adverse effects are, so we'll have to see, with more long-term monitoring as we start using these medications, what the benefits versus risks are for patients. But so far, I think the data is very promising for these agents, which is why I think that in the next few years you'll see a change in how we prescribe medications, and things like oveporexton might become the first-line agent for patients with hypersomnia.

Hypersomnia can be tricky to distinguish from conditions like narcolepsy type 2. What will attendees learn about sharpening that differential in everyday practice?

During my session, I'm going to talk a little bit about all the primary hypersomnias, including narcolepsy type 1, type 2, idiopathic hypersomnia, and Kleine-Levin syndrome. I'll start off by saying that as a practitioner, it's always important to first think about the secondary causes of hypersomnia, such as sleep apnea, or maybe they have heart failure, or something else systemic going on that's causing daytime sleepiness and fatigue. As a practitioner, we should always be on the lookout for those and rule them out before we start really thinking about primary hypersomnias.

But then, when we talk about primary hypersomnia, it can be difficult to distinguish clinically between someone who has idiopathic hypersomnia and narcolepsy type 2. Really, the best way to distinguish them is through sleep testing. The sleep maintenance sleep testing, or MSLT, is basically the opposite of the Maintenance of Wakefulness Test. We have them sit in a dark, quiet room and try to fall asleep, and we see how quickly they fall asleep and whether they have early REM onset in their sleep.

There are some cutoffs for this: if you fall asleep in less than 8 minutes on average and you have 2 early SOREMs, or early REMs, during your naps, you have narcolepsy type 1, if you also have cataplexy symptoms. If you don't have cataplexy symptoms, you have narcolepsy type 2. But for idiopathic hypersomnia, you don't need to have the SOREMs. You can have less than 8 minutes of sleep onset latency, or over 11 hours of sleep in 24 hours, which is called idiopathic hypersomnia of the long-sleep type.

So, there are a few different objective measures we can use. One of the things I'll talk about is that it's important to refer these kinds of patients when you think they have primary hypersomnia to a sleep specialist, so that we can do this testing and help interpret the results.

The other thing to think about is more the pathophysiology of the disease itself. All these primary hypersomnias probably have something to do with autoimmunity and inflammation in the system. We know, for example, that in narcolepsy type 1, orexin cells in the hypothalamus are dying off, and 90% of the cells are gone by the time you have significant symptoms. So, we can measure how much orexin someone is producing in the CSF. This has been done in multiple studies, and sometimes clinically we can measure CSF levels of orexin, and patients with less than 110 picograms, or less than a third of the normal value for whatever lab you're using, have narcolepsy type 1 by definition, based on CSF testing. These values change depending on whether you have narcolepsy type 2 or idiopathic hypersomnia. So that's another objective measure to help distinguish these things.

There are objective ways to distinguish the diagnosis and to help qualify patients for specific types of medications or treatments, but it needs more objective, careful testing not just a clinical diagnosis.

For neurologists, APPs, and primary care clinicians who don't specialize in sleep medicine, what's the single most practical or actionable point you hope they walk away with?

I'm going to give 2 points: one on diagnosis and one on treatment. If you come to the session, hopefully I'll give you a little more detail on the diagnosis, more specifically, I think for a general practitioner, it's important to rule out the secondary causes. Make sure we've done a hypothyroid workup, make sure they don't have heart failure, etc. I'll talk in a little more detail at that session about the common secondary causes of hypersomnia and the general workup we should consider before referring them for a more detailed sleep study for primary hypersomnias. So that's number one, for the diagnostic portion.

Number two is to be on the lookout for these new orexin agonists that are coming out. We'll probably be prescribing them soon, so be on the lookout and ask your patients if it's working and whether they have any adverse effects, because I think those are all important things to know for the future.

Transcript edited for clarity. For more information and to register for the symposium, click here.