The Optimal One-Month Dosing of Lemborexant for Moderate Obstructive Sleep Apnea (OSA) Patients With Low Arousal Threshold (LMOSALAT)

One-Month Dosing of Lemborexant for Treatment of Moderate OSA Patients With Low Arousal Threshold, a Randomized, Double-blind, Crossover, Placebo-Controlled Trial

The goal of this clinical trial is to investigate the 1-month treatment effects of different dose of lemborexant in moderate OSA adult patients (18-65 years of age) with low arousal threshold.

The main questions it aims to answer are:

Primary outcome measure: Apnea/hypopnea index (AHI)

Secondary outcome measure:

1. Polysomnography parameters

   • Mean and nadir oxygen saturation
   • Sleep efficiency
   • Wake after sleep onset (WASO)
   • Sleep latency
   • Rapid eye movement (REM) latency
   • Percentage of time spent in Non-rapid eye movement (NREM) stage 1-3 and REM stage
   • Arousal index
2. Oxford Sleep Resistance Test (OSLER) test
3. Epworth Sleepiness Scale (ESS)
4. Functional Outcome of Sleep Questionnaire-short version (FOSQ-10T)
5. Pittsburgh Sleep Quality Index (PSQI)

6. Actigraphy parameters

   • Total sleep time
   • Sleep efficiency
   • Wake after sleep onset (WASO)
   • Sleep latency

7. Sleep diary parameters (Appendix 5)

   • Total sleep time
   • Sleep efficiency
   • Wake after sleep onset (WASO)
   • Sleep latency
   • Sleep quality

Researchers will compare placebo to see if there is a difference in AHI.

Participants will

• participate a total of 3 phases of study (3-crossover trial)
• each phrase the participants will receive either lemborexant 5 mg, lemborexant 10 mg, or placebo orally per day for 30 days with 2-week washout (depend on intervention arm whether the participants receive which intervention sequence)
• complete three overnight in-laboratory polysomnography (2-week washout) at day 30 of each phrase
• monitor actigraphy during day 1 to 29 of intervention of all periods
• record sleep diary during day 1 to 29 of intervention of all periods
• complete the OSLER test in the morning of the three overnight test
• complete questionnaires including: Epworth Sleepiness Scale (ESS), Functional Outcome of Sleep Questionnaire-short version (FOSQ-10T), Pittsburgh Sleep Quality Index (PSQI) at baseline (prior to intervention) and the night before overnight in-laboratory polysomnography

Study Overview

• Status: Not yet recruiting
• Conditions: OSA - Obstructive Sleep Apnea
• Intervention / Treatment: Drug: Lemborexant 5 MG [Dayvigo] Period 1; Drug: Lemborexant 5 MG [Dayvigo] Period 2; Drug: Lemborexant 5 MG [Dayvigo] Period 3; Drug: Placebo Period 1; Drug: Placebo Period 2; Drug: Placebo Period 3; Drug: Lemborexant 10 MG [Dayvigo] Period 1; Drug: Lemborexant 10 MG [Dayvigo] Period 2; Drug: Lemborexant 10 MG [Dayvigo] Period 3

• Study Type: Interventional
• Enrollment (Estimated): 36
• Phase: Phase 2; Phase 1

Contacts and Locations

• Study Contact: Name: Sarocha Vivatvakin, MD; Phone Number: 66879310233; Email: sarocha.v@chula.ac.th
• Study Contact Backup: Name: Naricha Chirakalwasan, MD; Phone Number: 662-649-4037; Email: narichac@hotmail.com

Study Locations

• Thailand
  • Bangkok
    • Pathum Wan, Bangkok, Thailand, 10330
      • Chulalongkorn University
      • Contact: Sarocha Vivatvakin, MD; Phone Number: 66879310233; Email: sarocha.v@chula.ac.th

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion criteria

Individuals are eligible for participation in this study if they have all of the followings:

1. Patient, aged 18 - 65 years at the time of informed consent
2. Voluntary agreement and capable for giving written informed consent
3. Diagnosis with OSA according to the criteria of the International Classification of Sleep Disorders, version 3 Text Revision
4. Baseline screening polysomnography (PSG) demonstrated apnea-hypopnea index 15 - 30 events/h of sleep (moderate severity)
5. Patients identified as low arousal threshold using previously recommended criteria which allocated a score of 1 to each criterion: apnea-hypopnea index < 30 events per hour, nadir oxygen saturation as measured by pulse oximetry > 82.5%, and fraction of hypopneas > 58.3%. A score of 2 or above defined a low arousal threshold.
6. Peripheral capillary oxygen saturation (SpO2) ≥ 94% measured during screening visit
7. Habitually sleeping ≥ 5.5 hours/night with usual bedtime falls within the range of 9:00 PM to 1:00 AM
8. Body mass index 18 - 40 kg/m2 Exclusion criteria

Individuals were not eligible for participation in this study if they have any of the followings:

1. Previous allergy or adverse effects with Lemborexant or other sedatives
2. Pregnant or breastfeeding
3. Significant medical comorbidities that could affect individual safety and study assessment results, regarding investigators' opinion
4. Uncontrolled cardiovascular or cerebrovascular diseases
5. Neuromuscular diseases
6. Nasal anatomical defect
7. Significant psychiatric comorbidities that could affect individual safety and study assessment results, regarding investigators' opinion
8. Active respiratory disorders other than OSA
9. Central respiratory events (CAHI) >25% of the total AHI
10. Diagnosis/symptoms of sleep-related disease other than OSA including narcolepsy, restless legs syndrome, periodic limb movement disorder, or circadian rhythm sleep-wake disorder
11. Severe hypersomnolence (ESS ≥16)
12. Peripheral capillary oxygen saturation (SpO2) < 80% for ≥ 5% of total sleep time measured during screening visit
13. Driving-related sleepiness accident or near misses in the past 12 months
14. Safety-critical occupation
15. Using CPAP or other dental devices within 2 weeks of screening polysomnography until the end of the study
16. Unable to tolerate equipment in this study
17. Taking any medication that affects sleep or other variable measured in this study
18. Taking any medication with cytochrome P450 Family 3A (CYP3A) inhibitors and all CYP3A inducers
19. Drug or alcohol use disorder within 2 years before the study initiation or current excessive alcohol intake
20. Excessive caffeine intake

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Lemborexant 5 mg; Participants will receive two treatment sequences. Participants will complete three overnight sleep studies and cross-over with 2-week wash-out period The participants will receive lemborexant 5 mg per day before sleep for a total of 30 days. On the day 30 participants will receive the lemborexant 5 mg 5 minutes before lights-out at the sleep laboratory for overnight polysomnography. After 2 week wash-out period, the participants will cross to the placebo or lemborexant 10 mg arm with same repeat of another 2 phases.	Drug: Lemborexant 5 MG [Dayvigo] Period 1; Participants will receive lemborexant 5 mg per day for 30 days during first period; Drug: Lemborexant 5 MG [Dayvigo] Period 2; Participant will receive lemborexant 5 mg per day for 30 days during the second period; Drug: Lemborexant 5 MG [Dayvigo] Period 3; Participants will receive lemborexant 5 mg per day for 30 days during third period
Placebo Comparator: Placebo; Participants will receive two treatment sequences. Participants will complete three overnight sleep studies and cross-over with 2-week wash-out period The participants will receive placebo per day before sleep for a total of 30 days. On the day 30 participants will receive the placebo 5 minutes before lights-out at the sleep laboratory for overnight polysomnography. After 2 week wash-out period, the participants will cross to the lemborexant 5 or 10 mg arm with same repeat of another 2 phases.	Drug: Placebo Period 1; Participants will receive placebo 5 mg per day for 30 days during the first period; Drug: Placebo Period 2; Participant will receive placebo 5 mg per day for 30 days during the second period; Drug: Placebo Period 3; Participants will receive placebo per day for 30 days during third period
Experimental: Lemborexant 10 mg; Participants will receive two treatment sequences. Participants will complete three overnight sleep studies and cross-over with 2-week wash-out period The participants will receive lemborexant 10 mg per day before sleep for a total of 30 days. On the day 30 participants will receive the lemborexant 10 mg 5 minutes before lights-out at the sleep laboratory for overnight polysomnography. After 2 week wash-out period, the participants will cross to the placebo or lemborexant 5 mg arm with same repeat of another 2 phases.	Drug: Lemborexant 10 MG [Dayvigo] Period 1; Participants will receive lemborexant 10 mg per day for 30 days during first period; Drug: Lemborexant 10 MG [Dayvigo] Period 2; Participants will receive lemborexant 10 mg per day for 30 days during second period; Drug: Lemborexant 10 MG [Dayvigo] Period 3; Participants will receive lemborexant 10 mg per day for 30 days during third period

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Apnea/hypopnea index (AHI)	Apnea/hypopnea index (AHI) measured by polysomnography (scale: events/hour: minimum 0 event/hour - no maximum scoring; higher scores mean worse outcome)	At day 30 during the overnight in-laboratory of each study period

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean and nadir oxygen saturation	Mean and nadir oxygen saturation measured by polysomnography (scale: percent: minimum 0% - maximum 100%; higher scores mean better outcome)	At day 30 during the overnight in-laboratory of each study period
Sleep efficiency	Sleep efficiency measured by polysomnography (scale: percent: minimum 0% - maximum 100%; higher scores mean better outcome)	At day 30 during the overnight in-laboratory of each study period
Wake after sleep onset (WASO)	Wake after sleep onset (WASO) measured by polysomnography (scale: minute: minimum 0 minute - no maximum scoring; higher scores mean worse outcome)	At day 30 during the overnight in-laboratory of each study period
Sleep latency	Sleep latency measured by polysomnography (scale: minute: minimum 0 minute - no maximum scoring; higher scores mean worse outcome)	At day 30 during the overnight in-laboratory of each study period
REM latency	REM latency measured by polysomnography (scale: minute: minimum 0 minute - no maximum scoring; higher scores mean worse outcome)	At day 30 during the overnight in-laboratory of each study period
Percentage of time spent in NREM stage 1-3 and REM stage	Percentage of time spent in NREM stage 1-3 and REM stage measured by polysomnography (scale: percent: minimum 0% - maximum 100%; higher scores in NREM stage 3 and REM mean better outcome but higher scores in NREM stage 1 and 2 mean worse outcome)	At day 30 during the overnight in-laboratory of each study period
Arousal index	Arousal index measured by polysomnography (scale: events/hour: minimum 0 event/hour - no maximum scoring; higher scores mean worse outcome)	At day 30 during the overnight in-laboratory of each study period
OSLER error index	Oxford Sleep Resistance Test (OSLER) test (scale: events/hour: minimum 0 event/hour - no maximum scoring; higher scores mean worse outcome)	On the morning of the in-laboratory polysomnography
Epworth Sleepiness Scale (ESS)	Epworth Sleepiness Scale (ESS) questionnaires (scale: point: minimum 0 point - maximum 24 point; higher scores mean worse outcome)	Baseline (prior to intervention) and at day 30 of intervention before the overnight in-laboratory of each study period
Functional Outcome of Sleep Questionnaire-short version (FOSQ-10T)	Functional Outcome of Sleep Questionnaire-short version (FOSQ-10T) (scale: point: minimum 5 point - maximum 20 point; higher scores mean better outcome)	Baseline (prior to intervention) and at day 30 of intervention before the overnight in-laboratory of each study period
Pittsburgh Sleep Quality Index	Pittsburgh Sleep Quality Index (scale: point: minimum 0 point - maximum 21 point; higher scores mean worse outcome)	Baseline (prior to intervention) and at day 30 of intervention before the overnight in-laboratory of each study period
Total sleep time	Total sleep time measured by actigraphy (scale: minute: minimum 0 minute - no maximum scoring; higher scores mean better outcome)	During day 1-29 of intervention
Sleep efficiency	Sleep efficiency measured by actigraphy (scale: percent: minimum 0% - maximum 100%; higher scores mean better outcome)	During day 1-29 of intervention
Wake after sleep onset (WASO)	Wake after sleep onset (WASO) measured by actigraphy (scale: minute: minimum 0 minute - no maximum scoring; higher scores mean worse outcome)	During day 1-29 of intervention
Sleep latency	Sleep latency measured by actigraphy (scale: minute: minimum 0 minute - no maximum scoring; higher scores mean worse outcome)	During day 1-29 of intervention
Total sleep time	Total sleep time recorded by sleep diary (scale: minute: minimum 0 minute - no maximum scoring; higher scores mean better outcome)	During day 1-29 of intervention
Sleep efficiency	Sleep efficiency recorded by sleep diary (scale: percent: minimum 0% - maximum 100%; higher scores mean better outcome)	During day 1-29 of intervention
Wake after sleep onset (WASO)	Wake after sleep onset (WASO) recorded by sleep diary (scale: minute: minimum 0 minute - no maximum scoring; higher scores mean worse outcome)	During day 1-29 of intervention
Sleep latency	Sleep latency recorded by sleep diary (scale: minute: minimum 0 minute - no maximum scoring; higher scores mean worse outcome)	During day 1-29 of intervention
Sleep quality	Sleep quality recorded by sleep diary (5-point Likert scale of 1-5; higher score mean better outcome)	During day 1-29 of intervention

Collaborators and Investigators

• Sponsor: Chulalongkorn University
• Investigators: Principal Investigator: Sarocha Vivatvakin, MD, Department of Medicine, Faculty of Medicine

Study record dates

Study Major Dates

• Study Start (Estimated): September 1, 2026
• Primary Completion (Estimated): June 30, 2028
• Study Completion (Estimated): June 30, 2028

Study Registration Dates

• First Submitted: June 26, 2026
• First Submitted That Met QC Criteria: July 2, 2026
• First Posted (Actual): July 6, 2026

Study Record Updates

• Last Update Posted (Actual): July 6, 2026
• Last Update Submitted That Met QC Criteria: July 2, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Polysomnography; Lemborexant; Obstructive Sleep Apnea (OSA); Apnea/Hypopnea Index (AHI); Low Arousal Threshold
• Additional Relevant MeSH Terms: Nervous System Diseases; Respiratory Tract Diseases; Respiration Disorders; Sleep Wake Disorders; Signs and Symptoms, Respiratory; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Apnea Syndromes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Sleep Apnea, Obstructive; Apnea; lemborexant
• Other Study ID Numbers: 0594/69

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes