An insomnia drug didn't worsen breathing in severe sleep apnea, a small trial finds
Orexin antagonists were long avoided in sleep apnea over fears they'd suppress the arousals that end dangerous breathing pauses. Sixteen patients on daridorexant showed no meaningful change in breathing severity.
Orexin antagonists like daridorexant are approved for insomnia, but prescribing one to a patient with obstructive sleep apnea has carried a specific theoretical worry: by promoting sleep and potentially raising the arousal threshold, these drugs might suppress the very brain arousals that end a dangerous breathing pause, worsening rather than treating the underlying problem. A trial published this month in Sleep tests that concern directly in patients with severe, untreated apnea [s1].
The design
This randomized, double-blind, placebo-controlled, two-period crossover trial was conducted at a single sleep center in 16 adults with severe obstructive sleep apnea who did not also have insomnia [s1]. In each treatment period, participants received daridorexant 50 mg or placebo nightly for five days [s1]. The primary and secondary endpoints were the treatment difference in apnea-hypopnea index (AHI, breathing interruptions per hour) and oxygen saturation during total sleep time, measured after the last dose in each period [s1]. The trial prespecified thresholds for what would count as a clinically meaningful negative effect: a mean AHI increase of at least 10 events per hour, or a mean oxygen saturation decrease of 2 percentage points or more [s1]. Mean baseline AHI in the trial was severe: 51.2 events per hour, with oxygen saturation during sleep averaging 92.1% [s1].
What it found
No clinically meaningful effect of daridorexant on breathing severity was detected. The treatment difference in AHI was −3.7 events per hour (one-sided 95% CI ≤ +4.2) — meaning breathing events, if anything, trended slightly better, not worse, on daridorexant, and stayed well clear of the prespecified 10-event-per-hour threshold for concern [s1]. Oxygen saturation showed a similarly reassuring treatment difference of −0.12% (one-sided 95% CI ≥ −0.6%), also far from the prespecified 2-percentage-point threshold [s1].
On sleep itself, daridorexant increased total sleep time by 32.5 minutes compared with placebo (90% CI 6.9–58.2) and shortened the time it took to fall into persistent sleep by 10.3 minutes (90% CI −20.6 to −0.02), with a trend toward reduced wake after sleep onset that didn't reach statistical significance [s1]. Four adverse events were reported overall — three on daridorexant, one on placebo — all mild, and none related to respiratory function [s1].
Why this result matters for prescribing practice
This trial speaks to a genuine, mechanistically grounded safety question that has likely limited how comfortably clinicians prescribe orexin antagonists to patients who have both insomnia and sleep apnea — a combination, described elsewhere as COMISA, that isn't rare. Finding no meaningful worsening of breathing severity, in a population selected specifically for severe apnea (mean AHI over 51 events per hour) where any such effect should be most detectable, is a reassuring result for that theoretical concern, at least over this short exposure window.
What this doesn't establish
Sixteen participants over five days per treatment period is a small, short trial — well-suited to detecting an acute physiological safety signal like worsened breathing, which is what it was designed to do, but not powered or designed to establish long-term safety, effectiveness for treating comorbid insomnia in this population, or rarer adverse events. The trial specifically excluded people with comorbid insomnia, testing daridorexant's respiratory safety profile in isolation from its actual likely use case — most people prescribed an insomnia drug alongside sleep apnea treatment would have both conditions, not apnea alone. The five-night dosing window is also far short of how these drugs are typically used clinically, which is often for extended periods.
What to watch
Longer trials in patients with both sleep apnea and insomnia — the population where this safety question is most clinically relevant — and confirmation that the reassuring signal holds with extended use. Daridorexant is approved for insomnia, not sleep apnea; this article describes investigational use of an approved drug in a new context and is not medical advice.
Sources
Sources
More on
Not the oxygen drops: broken sleep tracked with depression, insomnia explained it
In 1,238 people from two community cohorts, apnea severity showed no link to depressive symptoms. Sleep fragmentation did, and that association disappeared once insomnia symptoms entered the model.
Waking in the night is the norm. Struggling to get back to sleep is not.
About a third of adults on two continents wake at least three nights a week. The 7.7% who cannot resume sleep carry almost all of the daytime damage — and the cause is often not what the sleeper thinks.
Patients with insomnia and apnea saw a bigger blood-pressure drop from CPAP
After four weeks, the comorbid-insomnia group's blood pressure fell 20 points more than the apnea-only group. The finding flips the usual framing of COMISA as simply a worse-outcomes phenotype.
Sleep apnea plus insomnia tripled mortality risk in a six-year cohort of 2,401 patients
Moderate-to-severe sleep apnea alone roughly doubled all-cause mortality risk. Adding comorbid insomnia to the same patients raised it further — evidence for treating the combination as its own risk category.