Tasimelteon Helped Adults Fall Asleep Earlier in Study
A new trial suggests the drug could help those with a chronic sleep timing disorder shift their sleep onset.
Updated on Oct. 5, 2026 in Sleep Disorders
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In a phase 3 trial, adults with delayed sleep-wake phase disorder saw a significant shift in sleep timing after using the drug tasimelteon for 28 days. Vanda Pharmaceuticals now intends to seek regulatory approval for this new use of the medication.
Why it matters
Delayed sleep-wake phase disorder often makes it difficult for individuals to fall asleep and wake up at conventional times, potentially impacting work and social function. This trial suggests a new treatment path for managing the condition as the company moves toward a formal application for the indication.
In a 28-day randomized trial of 40 adults with delayed sleep-wake phase disorder, those taking 20mg of tasimelteon achieved a 42.5-minute advancement in sleep onset compared to 5.4 minutes for those on a placebo. Researchers measured sleep timing changes using participant sleep diaries.
The players
Vanda Pharmaceuticals
A biopharmaceutical company focused on developing therapies for sleep and circadian rhythm disorders.
The details
Tasimelteon is a melatonin receptor agonist that works by helping to reset the bodys internal clock. In this trial, researchers administered 20mg of the drug daily to participants to assess its impact on sleep timing. The results showed that 60% of those treated with the drug fell asleep at least 30 minutes earlier, compared to only 15% of those in the placebo group.
Timeline
September 29, 2026: Vanda Pharmaceuticals released the study findings.
28 days: The total duration of the clinical trial treatment period.
Health Landscape
Tasimelteon is currently approved as Hetlioz for conditions including non-24-hour sleep-wake disorder and Smith-Magenis syndrome. This new clinical development follows the established precedent of the drug serving as a treatment for circadian rhythm disturbances.
If you struggle with chronic sleep onset delays, this trial highlights a potential future treatment option worth discussing with your doctor. Note that because this drug is currently only approved for other specific conditions, it is not yet a standard clinical treatment for sleep timing disorders.
The takeaway
Clinical trial results indicate that tasimelteon may help shift sleep schedules in adults with delayed sleep-wake phase disorder. If you have concerns about your own sleep timing, consult your physician to review current evidence-based approaches to circadian rhythm health.
Further reading
For more on managing circadian rhythm issues, visit the Sleep Disorders section.
More information
View the complete results in the Vanda Pharmaceuticals study news release.
Source note: This article includes information reported by Psychiatry Advisor.
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