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Study on the Effects of Tasimelteon for Patients with Delayed Sleep-Wake Phase Disorder

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying a condition known as Delayed Sleep-Wake Phase Disorder (DSWPD). This disorder affects the body's internal clock, making it difficult for individuals to fall asleep and wake up at conventional times. The study will evaluate the effects of a medication called tasimelteon, which is taken as a 20 mg hard capsule, compared to a placebo. Tasimelteon is designed to help regulate the sleep-wake cycle and improve sleep onset, which is the time it takes to fall asleep.

The purpose of the study is to assess how a daily dose of tasimelteon affects sleep onset over a 28-day period. Participants will be asked to keep a sleep diary to track changes in their sleep patterns. The study will also use a method called actigraphy, which involves wearing a device that monitors movement, to gather additional information about sleep patterns. Participants will take either tasimelteon or a placebo, which looks identical to the medication but does not contain the active substance, to compare the effects on sleep.

Throughout the study, various aspects of sleep will be evaluated, including the time it takes to fall asleep, total sleep time, and any sleep disturbances. The study will also look at how tasimelteon affects the body's internal clock, known as the circadian phase, and assess any changes in sleep-related impairments. Safety and tolerability of the medication will be monitored to ensure the well-being of participants. The study aims to provide valuable insights into the potential benefits of tasimelteon for individuals with DSWPD.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Randomization and initial dosing

    Upon joining the study, participants are randomly assigned to receive either tasimelteon or a placebo. The placebo is designed to look identical to the tasimelteon capsules.

    Participants begin taking a daily single oral dose of 20 mg of the assigned capsule. This is done to ensure the study remains double-blind, meaning neither the participants nor the researchers know who is receiving the actual medication.

  2. Step 2

    Treatment phase

    The treatment phase lasts for 28 days. During this time, participants continue to take their assigned capsule each day.

    Participants are required to maintain a sleep diary to record their sleep onset times and other sleep-related information. This helps in assessing changes in sleep patterns.

  3. Step 3

    Monitoring and assessment

    Throughout the study, participants' sleep patterns are monitored using both subjective methods, like sleep diaries, and objective methods, such as actigraphy, which involves wearing a device that tracks movement.

    Participants may also be asked to provide saliva samples to measure changes in circadian phase, which is the body's internal clock that regulates sleep-wake cycles.

  4. Step 4

    Completion and evaluation

    At the end of the 28-day treatment period, participants complete the study.

    The data collected from sleep diaries, actigraphy, and other assessments are analyzed to evaluate the effects of tasimelteon compared to the placebo on sleep onset and other sleep parameters.

Who can join the trial?

13 criteria

  • Must be able and willing to sign a written agreement to participate in the study.
  • Must have a sleep start time of midnight or later, recorded in a daily sleep diary, on at least 5 out of 7 days during the screening week.
  • Must complete the daily sleep diary at least 80% of the time during the screening period.
  • Must keep a consistent desired bedtime, within 15 minutes, on at least 5 out of 7 days during the initial phase of the study.
  • Must have a sleep start time that is at least 2 hours later than the desired bedtime, recorded in a daily sleep diary, on at least 5 out of 7 days during the initial phase of the study.
  • Must have a confirmed diagnosis of **Delayed Sleep-Wake Phase Disorder (DSWPD)**, according to the International Classification of Sleep Disorders-3.
  • Must be between 18 and 75 years old.
  • Must have a **Body Mass Index (BMI)** between 18 and 35. BMI is a measure of body fat based on weight and height.
  • Must be male, or a female who cannot become pregnant (due to surgery or menopause), or a female who can become pregnant but is using an effective method of birth control. Women who can become pregnant must also have a negative pregnancy test at specific times during the study.
  • Must be in good health based on medical history, physical exams, heart tests (ECG), blood tests, and urine tests.
  • Must be willing to follow study rules, including keeping a fixed sleep schedule and attending regular clinic visits.
  • Must have a desired bedtime that is at least 2 hours earlier than the usual sleep start time, as determined by a specific questionnaire. There must be at least a 2-hour difference between the reported sleep start time and the desired bedtime on at least 5 out of 7 days during the screening week.
  • Must have a sleep start time of midnight or later, as determined by a specific questionnaire.

Who cannot join the trial?

8 criteria

  • Individuals who are not diagnosed with Delayed Sleep-Wake Phase Disorder (DSWPD) cannot participate. This is a condition where a person's sleep is delayed by two or more hours beyond the conventional bedtime, causing difficulty in waking up at a desired time.
  • Participants who are unable to take a daily oral dose of the study medication.
  • Individuals who are not able to maintain a sleep diary for the duration of the study.
  • Participants who are not within the specified age range for the study.
  • Individuals who are not willing or able to comply with the study procedures.
  • Participants who have any other medical condition that might interfere with the study results.
  • Individuals who are currently participating in another clinical trial.
  • Participants who have a known allergy or adverse reaction to the study medication.
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Investigated drugs

Tasimelteon is a medication being studied for its effects on sleep patterns, specifically in people with Delayed Sleep-Wake Phase Disorder (DSWPD). This disorder affects the timing of sleep, making it difficult for individuals to fall asleep and wake up at conventional times. The trial aims to determine if tasimelteon can help regulate sleep onset, allowing participants to fall asleep more easily and at a more typical time.

What is already known about the treatment

Tasimelteon – Tasimelteon is administered orally in the form of a tablet, typically taken once daily. It is currently being studied in clinical trials for its effects on Delayed Sleep-Wake Phase Disorder (DSWPD). The main therapeutic indication for tasimelteon is to help regulate sleep patterns in individuals with this disorder. At the molecular level, tasimelteon works by targeting melatonin receptors in the brain, which are involved in the regulation of the sleep-wake cycle. It is classified pharmacologically as a melatonin receptor agonist.

Investigated diseases

Delayed Sleep-Wake Phase Disorder – This is a sleep disorder where a person's sleep is delayed by two or more hours beyond the conventional bedtime. This delay in falling asleep leads to difficulty in waking up at a desired time. Individuals with this disorder often experience sleep onset insomnia and excessive morning sleepiness. The condition is characterized by a stable but delayed sleep-wake pattern, which can interfere with daily activities. It is most common in adolescents and young adults, but can occur at any age. The disorder is not due to a lack of sleep, but rather a misalignment of the internal body clock with the external environment.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-516962-13-00Protocol codeVP-VEC-162-3502Estimated enrolment70 patientsSponsorVanda Pharmaceuticals Inc.

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