Phase 3 data on the orexin agonist oveporexton suggests that reducing microsleep frequency offers a more accurate reflection of real-world treatment response than traditional wakefulness tests alone.
By Sree Roy
Traditionally, the success of therapeutic interventions for excessive daytime sleepiness is measured through the Maintenance of Wakefulness Test (MWT) and the Multiple Sleep Latency Test (MSLT), both of which prioritize “sleep onset latency”—the number of minutes a patient can remain awake or how quickly they fall asleep. However, these metrics may fail to capture the nuanced “quality of wakefulness” that patients experience between those measured intervals.
New data revealed at SLEEP 2026 suggests that focusing on microsleeps—three- to 15-second periods of sleep prior to sleep onset—could provide a more granular understanding of disease burden and treatment efficacy. In two randomized, double-blind, phase 3 studies, the oral orexin receptor 2-selective agonist oveporexton, a Takeda Pharmaceuticals drug candidate, significantly reduced microsleep rates and delayed the onset of the first microsleep in patients with narcolepsy type 1 (NT1) in MWTs. The findings indicate that addressing these fleeting intrusions of sleep may be as critical as extending the time to full sleep onset.
“The microsleeps present a better way to describe the effect that oveporexton has on wakefulness in real-life circumstances,” says Elena Koundourakis, PhD, global program leader for the Takeda orexin franchise. “It really contributes to the ‘quality of the wake’ of patients. In other words,in the MWT, they may force themselves to stay awake.” But the microsleeps could unveil their real-life burden.
Limitations of Mean Sleep Onset Latency
In the context of clinical trials, mean sleep onset latency provides a clear, quantifiable number that regulatory bodies can use to evaluate whether a drug helps a patient stay awake longer. Yet, in clinical practice, sleep onset latency does not always correlate with a patient’s subjective experience of feeling awake.
A patient may technically remain “awake” for the duration of a 40-minute MWT trial, even if they experienced dozens of three-second microsleeps during that window. In a laboratory setting, this is recorded as a successful wake trial; in the real world, those three seconds could occur while the patient is operating a motor vehicle.
The phase 3 results for oveporexton, reported by Yishu Gong, PhD, MPH, and colleagues, sought to look beyond the binary of wake versus sleep. The researchers identified microsleeps and artificial intelligence (AI)-derived sleepiness scores from electroencephalography (EEG) recordings as biomarkers for excessive daytime sleepiness. By analyzing the quality of the wake period prior to sleep onset, the study aimed to bridge the gap between clinical trial metrics and the daily realities of living with NT1.
The First Light and Radiant Light Studies
The data presented at SLEEP 2026 were derived from two pivotal studies: The First Light (158 participants) and The Radiant Light (105 participants), in which participants ranged in age from 16 to 70 years. Participants were randomized to receive oveporexton (1 mg or 2 mg doses) or a placebo, with the first dose administered at 8 AM.
To assess the fluctuations in sleepiness throughout the day, MWT sessions consisted of four 40-minute wake trials conducted at 10 AM, 12 PM, 2 PM, and 4 PM. While the primary endpoint focused on sleep onset latency, the exploratory data on microsleeps revealed a stark contrast between the treated and placebo groups:
- Reduction in Microsleep Rates: In all oveporexton-treated groups across both studies, microsleep rates decreased significantly. At baseline, patients averaged approximately three microsleeps per 10 minutes. Following 12 weeks of treatment, this rate dropped to less than one microsleep per 10 minutes.
- Time-to-First Microsleep: Oveporexton-treated groups experienced a prolonged duration before the first microsleep occurred compared to the placebo group.
- Consistency in Duration: Interestingly, the average duration of the microsleeps themselves (for those who still experienced them) did not change significantly, suggesting the drug’s primary impact is on the frequency and onset of these events rather than their individual length.
Safety Implications of the ‘Quality of Wake’
The clinical significance of reducing microsleeps extends far beyond the sleep lab. For patients with narcolepsy, the fear of a sudden “sleep attack” can be secondary to the constant, low-level intrusion of microsleeps that degrade cognitive function and safety.
Koundourakis emphasizes that driving is perhaps the most critical real-life application of these findings. “When the microsleep happens when a patient is driving, it can be really, really dangerous,” she says. “This is one of the most bothersome symptoms for patients. Many tell us that they have stopped driving, despite being on treatment. So, we believe that by affecting microsleeps, oveporexton would suggest that we can modulate the driving as one of what we call ‘quality of wake.’”
For the sleep tech, these findings underscore the importance of meticulous EEG scoring. While traditional scoring focuses on 30-second epochs to determine sleep stages, the identification of 3- to 15-second microsleeps requires a more granular approach. The use of AI-derived scores in the Takeda trials suggests a future where automated systems could assist in identifying these brief but clinically significant events, providing physicians with a more complete “wakefulness profile” for their patients.
Moving Toward New Clinical Biomarkers
While a foundational diagnostic tool, the MSLT has faced criticism for being static and artificial, failing to mimic the environmental demands a patient faces in daily life.
The introduction of microsleep frequency as a potential biomarker could offer a more dynamic way to measure treatment response. If a drug can be shown to not only extend the time to sleep but also to clean up the wake period by eliminating microsleeps, it provides a stronger argument for the drug’s efficacy in improving a patient’s functional status.
“Microsleeps seems to be really quite an important real-life outcome that [clinicians] can grasp”—one that speaks to the limitations of the MSLT, Koundourakis says. “So there seems to be a willingness to adopt microsleeps in clinical practice.”
The potential for microsleeps to serve as a digital biomarker is also gaining traction. As wearable technology and home-based EEG monitoring become more sophisticated, the ability to track microsleeps in a patient’s natural environment could revolutionize how narcolepsy is managed. Instead of a once-a-year lab visit, physicians could potentially monitor “quality of wake” trends over weeks or months.
For the sleep physician, this means that a patient who reports feeling better on an orexin agonist, even if their MWT scores are similar to those on other medications, may be experiencing a genuine reduction in microsleep intrusions that traditional metrics are simply not designed to catch.
Reference
Gong Y, Maski K, Mignot E, et al. 0742 Treatment with an orexin agonist reduces microsleeps and improves wakefulness during MWT in people with NT1: Phase 3 results. Sleep. 2026 May;49(Suppl 1):A331.
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