Idorsia daridorexant Phase 2 shows sleep gains in paediatric insomnia

Idorsia has presented Phase 2 data showing its dual orexin receptor antagonist (DORA) daridorexant produced statistically significant, dose-dependent increases in total sleep time in children and adolescents with insomnia disorder. The results, unveiled at Sleep Europe 2026 in Maastricht, mark the first controlled evidence that a DORA can meaningfully extend sleep duration in a paediatric population.

The randomised, double-blind, placebo-controlled study (NCT05423717) enrolled 165 participants aged 10 to under 18 years with DSM-5 insomnia disorder and tested 10, 25 and 50 mg doses over two weeks. More than half of participants had a diagnosed or subthreshold neurodevelopmental disorder, including autism spectrum disorder and/or ADHD. The primary endpoint, change from baseline in objectively measured total sleep time on day one, was met with statistical significance (p=0.0185).

At the 50 mg dose, participants gained 50 minutes of objective total sleep time versus a 20-minute gain with placebo. In the neurodevelopmental subgroup, the gain reached 64 minutes against 27 minutes for placebo. After two weeks, caregiver-reported sleep time at 50 mg had increased by approximately 69 minutes, compared with around 30 minutes for placebo. The safety profile at all doses was reported as consistent with the established adult profile, with adverse event rates at 50 mg comparable to placebo and no signals of dependence or withdrawal.

Clinical significance

Professor Carmen Schröder of Strasbourg University Hospitals, who led the study, described the findings as a "strong foundation" for paediatric development. She noted that insomnia in children with neurodevelopmental disorders compounds core symptoms and comorbidities, while pharmacological options remain absent in the United States, where no approved drug therapies exist for paediatric insomnia disorder. Idorsia said it expects to initiate a Phase 3 programme in the second half of next year, pending consolidation of feedback from global health authorities on the study protocol.

The company also presented 15 further abstracts covering adult populations, including real-world evidence from prospective and retrospective studies showing improvements in insomnia severity, depressive symptoms, quality of life and work productivity alongside sleep gains. A separate prescribing-pattern analysis across six countries found that increasing DORA use coincided with reductions in benzodiazepine and Z-drug prescribing, though overall insomnia medication volumes were unchanged.

Market and competitive context

The adult insomnia market is already contested by two approved DORAs: suvorexant (Merck's Belsomra, approved 2014) and lemborexant (Eisai's Dayvigo, approved 2019). Daridorexant, marketed as QUVIVIQ, received FDA approval for adults in January 2023 and European approval the same year. Idorsia's paediatric Phase 2 data position it as the sole DORA to have generated controlled paediatric evidence, a meaningful regulatory and commercial differentiator if Phase 3 confirms the effect.

The paediatric insomnia space has historically been underserved because of the regulatory complexity and ethical requirements associated with trials in minors, which has deterred many developers. A successful Phase 3 programme would likely qualify for FDA Paediatric Priority Review and could attract a Rare Pediatric Disease voucher if Idorsia targets a sub-indication meeting that threshold. European regulators have also been pressing sponsors to include paediatric investigation plans earlier in development cycles, a dynamic that may accelerate MHRA and EMA engagement once Phase 3 is under way.

Idorsia noted the full Phase 2 dataset manuscript is under evaluation at a peer-reviewed journal, and a recording of Professor Schröder's Sleep Europe presentation has been made publicly available. Investors will be watching for the Phase 3 protocol design and any update on commercial partnership arrangements for daridorexant beyond the company's existing Asia-Pacific and Middle East deals.