Efficacy of Lemborexant in Adults ≥ 65 Years of Age with Insomnia Disorder.

BACKGROUND: Pharmacologic treatments are available to treat insomnia, a common and burdensome sleep disorder, but may be contraindicated in older adults who are prone to side effects from sleep-promoting drugs. These analyses of sleep diary data from Study E2006-G000-303 (Study 303) investigated the benefits of lemborexant 5 mg (LEM5) and 10 mg (LEM10) in the subgroup age ≥ 65 years with insomnia. METHOD: Study 303, a 12-month, double-blind study of LEM5 and LEM10 in adults (age ≥ 18 years) with insomnia disorder (sleep onset and/or maintenance difficulties) assessed subject-reported (subjective) sleep-onset latency (sSOL), sleep efficiency (sSE), wake after sleep onset (sWASO), and total sleep time (sTST). Morning sleepiness/alertness, insomnia severity (Insomnia Severity Index [ISI]), fatigue (Fatigue Severity Scale [FSS]), perceptions of sleep-related medication effects (Patient Global Impression-Insomnia [PGI-I] questionnaire), and safety were also evaluated. RESULTS: In this subgroup of older adults (≥ 65 years; n = 262), there were significantly larger changes from baseline for sSOL, sSE, sTST, and sWASO with LEM5 and LEM10 versus placebo through month 6 (except sWASO month 1), indicating improvement; these improvements were sustained through month 12. Subject-reported increases in morning alertness were significantly greater with one or both LEM doses versus placebo through month 6 and sustained through month 12. There were significantly larger ISI total and daytime functioning score decreases (improvement) from baseline with LEM versus placebo at months 1, 3, and 6 (total score: both doses; daytime functioning: LEM5 month 1 and both doses months 3 and 6) and decreases from baseline FSS at months 1 and 3 (LEM5) and month 6 (both doses), sustained to month 12. Compared with placebo, more subjects reported that LEM (both doses) positively impacted ability to sleep, time to fall asleep, and TST through month 6, sustained to month 12, with no rebound after drug withdrawal. LEM was well tolerated to month 12; mild somnolence was the most common treatment-emergent adverse event. CONCLUSIONS: Improvements in subject-reported efficacy in LEM-treated adults age ≥ 65 years with insomnia were observed as early as the first week of treatment and sustained through end of month 12. LEM was well tolerated. CLINICAL TRIALS REGISTRATION: ClinicalTrials.gov identifier NCT02952820: E2006-G000-303; Study 303; SUNRISE-2 (First posted: October 2016); EudraCT 2015-001463-39 (First posted: November 2016).

Insomnia is a common sleep disorder associated with significant difficulties, particularly in older adults. Although there are many drug treatments available, some are associated with the important risk of side effects and may not adequately treat sleep maintenance (ability to stay asleep), which is a frequent sleep complaint in older people. Lemborexant has been approved in multiple countries for the treatment of adults with insomnia based on studies that show lemborexant improved adults' ability to fall asleep and stay asleep and is well tolerated. To examine the long-term benefit of lemborexant, we investigated subject-reported benefits and safety of lemborexant in older (≥ 65 years) adults who participated in a 1-year study. The results showed that within the first few days of taking lemborexant, and lasting through 12 months of treatment, nightly lemborexant improved nighttime sleep (that is, it reduced the time it took to fall asleep, reduced the time awake during the night, and increased total sleep time) more than placebo. Morning alertness improved more in older adults who took lemborexant compared with placebo. In addition, those who took lemborexant also reported that their insomnia symptoms were less severe and they had less fatigue compared with placebo. Lemborexant was well tolerated in older adults. These results suggest that lemborexant may be a good option for older adults with insomnia disorder.

Efficacy and safety of lemborexant in subjects previously treated with placebo for 6 months in a randomized phase 3 study.

OBJECTIVE/BACKGROUND: To examine the effects of lemborexant (LEM) 5 mg (LEM5) or LEM 10 mg (LEM10) following extended placebo treatment. This post-hoc analysis used subject-reported sleep outcomes data from a phase 3 trial. PATIENTS/METHODS: The subjects in these post-hoc analyses were randomized to placebo for 6 months (Time Period [TP]1) in Study E2006-G000-303 (SUNRISE-2; NCT02952820). Following placebo exposure, subjects were re-randomized to LEM5 or LEM10 for another 6 months (TP2). Subject-reported sleep outcomes derived from sleep diaries included sleep onset latency (sSOL), wake after sleep onset (sWASO), sleep efficiency (sSE), and total sleep time (sTST). Magnitude and change rate in parameters were assessed for 7 days before/after initial randomization to placebo and 7 days before/after re-randomization to LEM (6 months later). Month 6 placebo non-responders were assessed for LEM response in TP2 using predetermined responder definitions. Safety was monitored throughout the study. RESULTS: Overall, 321 subjects received placebo; 258 re-randomized subjects received LEM5 (n = 133) and LEM10 (n = 125). Subjective sleep outcomes improved during TP1 with approximately 62 subjects (∼20%) exhibiting a sustained placebo response. Upon re-randomization to LEM, all measures showed an additional incremental benefit, most prominently in sSOL and sTST. Among Month 6 placebo non-responders, 11%-15% subsequently responded to LEM as assessed at Month 12. The safety profile was similar between treatment periods and treatment groups. CONCLUSIONS: These data suggest that even when insomnia symptoms have improved over time with placebo treatment, additional and sustained clinical gains in sleep outcomes are possible with active treatment using lemborexant.

Efficacy and safety of lemborexant in midlife women with insomnia disorder.

OBJECTIVE: Insomnia is common in midlife women. The efficacy and safety of lemborexant (LEM), a competitive dual orexin receptor antagonist, was assessed for 12 months in a subgroup of midlife women (age, 40-58 y) from Study E2006-G000-303 (Study 303; SUNRISE-2). METHODS: This was a randomized, double-blind, placebo (PBO)-controlled (first 6 mo) study of adults with insomnia disorder ( N = 949). During treatment period 1 (TP1), participants received PBO or LEM 5 mg (LEM5) or 10 mg (LEM10). During TP2 (second 6 mo), LEM participants continued their assigned dose; PBO participants were rerandomized to LEM5 or LEM10. Assessments included patient-reported sleep- and fatigue-related measures and treatment-emergent adverse events. RESULTS: The midlife female subgroup comprised 280 of 949 participants (TP1: PBO, n = 90 of 318 [28.3%]; LEM5, n = 82 of 316 [25.9%]; LEM10, n = 108 of 315 [34.3%]). At 6 months, median changes from baseline in subjective sleep-onset latency (in minutes) were -17.9, -20.7, and - 30.4 for PBO, LEM5, and LEM10 (vs PBO: LEM5, P = not significant; LEM10, P = 0.0310). At 6 months, mean changes from baseline in subjective wake after sleep onset (in minutes) were -37.0 (59.6), -50.1 (74.5), and -54.5 (65.4) for PBO, LEM5, and LEM10 (vs PBO: LEM5 and LEM10, P = not significant), with benefits sustained through 12 months. Greater decreases from baseline (improvement) in Insomnia Severity Index total score and Fatigue Severity Scale total score were seen with LEM versus PBO at 6 months; benefits continued through 12 months. Most treatment-emergent adverse events were mild to moderate in severity. CONCLUSIONS: Consistent with the total population, subjective sleep parameters improved, and improvement was sustained over time in midlife women. LEM was well tolerated, suggesting that LEM may be a potential treatment option for midlife women with insomnia.

Effect of discontinuation of lemborexant following long-term treatment of insomnia disorder: Secondary analysis of a randomized clinical trial.

Discontinuing long-term pharmacotherapy for insomnia can result in rebound insomnia or withdrawal symptoms and suboptimal treatment. Post hoc analyses evaluated rebound insomnia and withdrawal symptoms among the subset of subjects from a phase III, 12-month, global, multicenter, randomized, double-blind, parallel-group study who completed 12 or 6 months of active treatment and follow-up period. Study E2006-G000-303 (Study 303) included adults (N = 655) with subjective sleep-onset latency ≥30 min and/or subjective wake-after-sleep onset ≥60 min at least three times weekly during the 4 weeks before enrollment. Subjects were randomized 1:1:1 to lemborexant 5 mg (LEM5) or 10 mg (LEM10) or placebo for 6 months. Thereafter, for an additional 6 months, LEM5- and LEM10-treated subjects continued lemborexant and the placebo group was rerandomized 1:1 to LEM5 or LEM10. Month 12 was followed by abrupt discontinuation and a 2-week end-of-study follow-up. Using daily electronic sleep diaries, patients reported (subjective) sleep end points (sleep-onset latency, wake-after-sleep onset, sleep efficiency, and total sleep time). Withdrawal symptoms were assessed using the Tyrer Benzodiazepine Withdrawal Symptoms Questionnaire (T-BWSQ). Sleep outcome improvements with lemborexant at month 12 were generally maintained throughout the 2-week off-treatment period wherein <20% of subjects experienced significant worsening of insomnia symptoms versus screening. There was no evidence of withdrawal symptoms by T-BWSQ following lemborexant discontinuation. This analysis demonstrates rebound insomnia is unlikely to occur with lemborexant, and its effectiveness is maintained after abrupt discontinuation without placebo replacement following 6-12 months of treatment.

Efficacy and safety of lemborexant over 12 months in Asian adults with insomnia disorder.

Study objectives: Lemborexant (LEM) is a dual orexin receptor antagonist approved for treating adults with insomnia. We analyzed the efficacy (subjective sleep outcomes) and safety of LEM over 12 months in the subgroup of Asian subjects from Study E2006-G000-303 (Study 303). Methods: Study 303 was a 12-month, randomized, placebo-controlled (first 6 months), double-blind, parallel-group, phase 3 study of adults with insomnia disorder. During the 6-month Period 1, subjects were randomized (1:1:1) to placebo, LEM 5 mg (LEM5), or LEM 10 mg (LEM10); LEM subjects continued treatment in the following 6-month Period 2. Outcome measures included subject-reported (subjective) sleep onset latency (sSOL), sleep efficiency (sSE), wake after sleep onset (sWASO), total sleep time (sTST), Insomnia Severity Index (ISI), and Patient Global Impression-Insomnia version (PGI-I). Treatment-emergent adverse events (TEAEs) were assessed. Results: Overall, 178 Asian subjects (Japanese, n = 161; Chinese, n = 4; other Asian, n = 13) were included. Greater decreases in sSOL and sWASO and increases in sSE and sTST from baseline were observed with LEM vs placebo at 6 months; LEM benefits were sustained through 12 months. Greater decreases in ISI total score were seen with LEM vs placebo at 6 months; improvements from baseline with LEM continued through 12 months. For each PGI-I item, LEM-treated subjects had more positive medication effects than placebo-treated subjects at 6 months; these effects were maintained with LEM in Period 2. TEAEs were generally mild to moderate. Conclusions: LEM improved subjective sleep parameters and was well-tolerated in Asian subjects with insomnia disorder over 12 months. Clinical trial registration: ClinicalTrials.gov, NCT02952820; ClinicalTrialsRegister.eu, EudraCT Number 2015-001463-39.

Improvement in fatigue and sleep measures with the dual orexin receptor antagonist lemborexant in adults with insomnia disorder.

OBJECTIVE: Fatigue is a common symptom in patients with insomnia. This analysis evaluated whether treatment of nighttime symptoms of insomnia with a dual orexin receptor antagonist, lemborexant, might also reduce fatigue. METHODS: Analyses were conducted of two phase 3 studies of subjects with insomnia disorder. Subjects received placebo, lemborexant 5 mg, or lemborexant 10 mg in the 12-month (6 months placebo-controlled) Study E2006-G000-303 (Study 303: SUNRISE-2) of adults (N = 949; full analysis set [FAS]), and the 1-month, placebo- and active-controlled Study E2006-G000-304 (Study 304; SUNRISE-1) of older adults (females ≥55 years, males ≥65 years) (N = 1006; FAS). Fatigue was assessed using the Fatigue Severity Scale (FSS). Patient-reported sleep onset and maintenance endpoints were analyzed using data from electronic sleep diaries. RESULTS: Lemborexant significantly reduced subject-reported fatigue versus placebo over a 6-month treatment period (FSS total score least-squares mean treatment difference of -2.50 for 5 mg and -2.56 for 10 mg of lemborexant; p < 0.05 for both). This reduction was sustained over 12 months of lemborexant in both the overall population and in subjects with clinically meaningful fatigue (FSS total score ≥36) at baseline. Improvements in fatigue over time positively correlated with improvements in sleep onset and maintenance parameters. Improvements in sleep quality were evident as early as 1 week after lemborexant treatment, whereas longer-term treatment (>1 month) may be needed for improvements in insomnia-related fatigue. CONCLUSIONS: In addition to improving sleep onset and sleep maintenance in subjects with insomnia disorder, lemborexant provides further benefit by reducing daytime fatigue. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT02952820 and https://clinicaltrials.gov/ct2/show/NCT02783729. ABBREVIATIONS: DSM-5 = Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition; FSS = Fatigue Severity Scale; ICSD-3 = International Classification of Sleep Disorders, Third Edition; LSM = least squares mean; sSE = subjective sleep efficiency; sSOL = subjective sleep onset latency; sTST = subjective total sleep time; sWASO = subjective sleep after wake onset.

Impact of lemborexant treatment on insomnia severity: analyses from a 12-month study of adults with insomnia disorder.

OBJECTIVE/BACKGROUND: Evaluate changes in insomnia severity in subjects with moderate to severe insomnia (Insomnia Severity Index [ISI] score ≥15) treated for 12 months nightly with lemborexant. PATIENTS/METHODS: This phase 3 randomized study comprised two 6-month treatment periods. In Period 1, 949 subjects were randomized to placebo, lemborexant 5 mg (LEM5) or 10 mg (LEM10). In Period 2, placebo subjects were rerandomized to LEM5 or LEM10; subjects initially randomized to lemborexant continued their assigned treatment. Insomnia severity was assessed using baseline ISI and 1-, 3-, 6-, 9-, and 12-month post-treatment scores. RESULTS: Mean ISI scores improved significantly across treatment groups and disease severities, with greater decreases from baseline in the LEM5 and LEM10 versus placebo groups at months 1 (-7.1, -7.2, -5.2, respectively), 3 (-8.6, -8.9, -6.1, respectively), and 6 (-9.9, -9.8, -7.2 respectively); ISI score improvements were maintained with LEM5 and LEM10 at months 9 (-11.1 and -11.2, respectively) and 12 (-11.5 and -11.2, respectively). At months 1, 3, and 6, significantly more treatment responders (≥7-point ISI score decrease from baseline) were observed with LEM5 (44%-57%) and LEM10 (44%-52%) versus placebo (30%-41%). At months 1, 3, and 6, more remitters (ISI total score <10 and < 8) were observed with LEM5 (30%-44% and 22%-34%, respectively) and LEM10 (31%-41% and 22%-31%, respectively) versus placebo (18%-28% and 11%-21%, respectively). CONCLUSIONS: Lemborexant significantly reduced insomnia severity for 12 months and increased clinically meaningful response and remission rates versus placebo. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT02952820; ClinicalTrialsRegister.eu, EudraCT Number 2015-001463-39.

Long-term effectiveness and safety of lemborexant in adults with insomnia disorder: results from a phase 3 randomized clinical trial.

OBJECTIVE/BACKGROUND: Lemborexant is a dual orexin receptor antagonist approved in the United States, Japan, and Canada for the treatment of insomnia in adults. We report effectiveness and safety outcomes in subjects with insomnia who received up to twelve months of continuous lemborexant treatment in Study E2006-G000-303 (Study 303; SUNRISE-2). PATIENTS/METHODS: Study 303 was a twelve-month, global, multicenter, randomized, double-blind, parallel-group, Phase 3 study divided into two treatment periods. In Treatment Period 1 (first six months), subjects (n = 949, Full Analysis Set) were randomized to daily placebo, lemborexant 5 mg (LEM5) or lemborexant 10 mg (LEM10). In Treatment Period 2 (second six months), placebo subjects were rerandomized to LEM5 or LEM10, and subjects randomized to lemborexant continued their assigned treatment (LEM5, n = 251; LEM10, n = 226). Sleep onset and sleep maintenance endpoints were analyzed from daily electronic sleep diary data. Treatment-emergent adverse events (TEAEs) were monitored. RESULTS: For all sleep parameters, the significant benefits observed with LEM5 and LEM10 versus placebo over six months were maintained at twelve months in subjects who received twelve continuous months of treatment. There was no evidence of rebound insomnia or withdrawal in either lemborexant group following treatment discontinuation. Over twelve months of lemborexant treatment, most TEAEs were mild/moderate; the most common TEAEs were nasopharyngitis, somnolence and headache. CONCLUSIONS: LEM5 and LEM10 had significant benefit on sleep onset and sleep maintenance compared with placebo, and importantly, lemborexant effectiveness persisted at twelve months, suggesting that lemborexant may provide long-term benefits for subjects with insomnia. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT02952820; ClinicalTrialsRegister.eu, EudraCT Number 2015-001463-39.

Assessment of morning sleep propensity with lemborexant in adults with insomnia disorder in a randomized, placebo-controlled crossover study.

Objective: To evaluate effects of lemborexant (LEM), a dual orexin receptor antagonist, on next-morning sleep propensity assessed by a modified Multiple Sleep Latency Test (M-MSLT) in adults with insomnia disorder. Methods: Study 107 (E2006-A001-107) was a phase 1, randomized, double-blind, four-period crossover study. Subjects (n = 69) received oral single-dose placebo, LEM 5 mg (LEM5), and LEM 10 mg (LEM10) at bedtime in periods 1-3 in a randomized crossover and open-label flurazepam 30 mg in period 4. After an 8-hour overnight sleep opportunity, the M-MSLT measured average sleep onset latency (SOL). Mean change from baseline in average SOL versus placebo of -6.0 min or more was considered clinically meaningful. Other sleep propensity assessments included the proportion of subjects with average SOL >6 min shorter than placebo. LEM plasma concentrations, safety, and tolerability were also assessed. Results: M-MSLT assay sensitivity was confirmed by a clinically meaningful decrease in average SOL with flurazepam versus placebo (least squares mean [LSM] difference -6.06 min; 1-sided p < 0.0001). In contrast, decreases in average SOL with LEM5 (LSM difference vs. placebo -1.15 min; 1-sided p = 0.0262) and LEM10 (-3.48 min; p < 0.0001) did not meet the predefined threshold for a clinically meaningful effect (LEM5, -2.12; LEM10, -4.46). Some individuals did experience higher sleep propensity (average SOL >6.0 min shorter than placebo), particularly with LEM10 (LEM10, 29.4%; LEM5, 13.2%). Conclusions: In contrast to flurazepam, LEM5 and LEM10 did not show clinically meaningful mean increases in next-morning sleep propensity versus placebo. The possibility that some subjects may experience residual morning effects cannot be excluded. Clinical trial registration: ClinicalTrials.gov, NCT02350309.

Lack of residual morning effects of lemborexant treatment for insomnia: summary of findings across 9 clinical trials.

OBJECTIVES: Residual next-day effects of sleep-promoting drugs are common and an important safety issue. Lemborexant is a dual orexin receptor antagonist approved in the United States and Japan for treatment of insomnia in adults. We evaluated the potential of lemborexant for residual morning and next-day effects, including somnolence, based on lemborexant clinical study findings. METHODS: This paper reports findings from 9 lemborexant clinical studies that incorporated next-day assessments of residual drug effects, based on published findings and data on file. Results are reported for healthy subjects or subjects with insomnia disorder treated with lemborexant 5 mg/day or 10 mg/day, placebo, or active comparator before bedtime. Outcomes assessed included next-morning postural stability (body sway measured by ataxiameter), cognitive performance (Cognitive Performance Assessment Battery), impact on driving (standard deviation of lateral position during highway driving test), subjective sleepiness (sleep diary entries), and adverse events of somnolence. RESULTS: Change from baseline in postural stability the morning after lemborexant administration did not differ from placebo. Among 4 Cognitive Performance Assessment Battery measures, only power of attention declined significantly more with lemborexant treatment compared with placebo in 1 of 2 studies, whereas zolpidem differed from placebo on multiple measures. On the highway-driving test, lemborexant did not significantly impair driving performance versus placebo, however, zopiclone did differ. In large phase 3 trials, next-morning sleep diary ratings showed significantly greater alertness with lemborexant compared with placebo after up to 6 months of treatment. As expected, somnolence was the most common adverse event reported with lemborexant treatment. Somnolence was typically mild to moderate in severity and rarely caused discontinuation of study drug. CONCLUSION: Across 9 clinical studies, lemborexant did not substantially impair next-day functioning among healthy subjects and subjects with insomnia.

Long-term efficacy and tolerability of lemborexant compared with placebo in adults with insomnia disorder: results from the phase 3 randomized clinical trial SUNRISE 2.

STUDY OBJECTIVES: To assess long-term efficacy and safety of lemborexant (LEM), a novel dual orexin receptor antagonist, versus placebo in adults with insomnia disorder. METHODS: This was a 12-month, global, multicenter, randomized, double-blind, parallel-group phase 3 study comprising a 6-month placebo-controlled period (reported here) followed by a 6-month active-treatment-only period (reported separately). A total of 949 participants with insomnia (age ≥18 years) were randomized, received treatment with an oral dose of placebo or LEM (5 mg [LEM5] or 10 mg [LEM10]) and were analyzed. Sleep onset and sleep maintenance endpoints were analyzed from daily electronic sleep diary data. Treatment-emergent adverse events (TEAEs) were monitored throughout the study. RESULTS: Decreases from baseline in patient-reported (subjective) sleep onset latency and subjective wake after sleep onset, and increases from baseline in subjective sleep efficiency, were significantly greater with LEM5 and LEM10 versus placebo. Significant benefits over placebo were observed at the end of month 6, and at most time points assessed over the 6-month period, indicating long-term sustained efficacy of LEM. A significantly greater percentage of sleep onset responders and sleep maintenance responders were observed with LEM treatment versus placebo. Participants treated with LEM reported a significant improvement in quality of sleep after 6 months versus placebo. The majority of TEAEs were mild or moderate. There was a low rate of serious TEAEs and no deaths. CONCLUSIONS: LEM5 and LEM10 provided significant benefit on sleep onset and sleep maintenance in individuals with insomnia disorder versus placebo, and was well tolerated. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT02952820; ClinicalTrialsRegister.eu, EudraCT Number 2015-001463-39.

On-the-road driving performance the morning after bedtime administration of lemborexant in healthy adult and elderly volunteers.

STUDY OBJECTIVES: To assess potential effects of lemborexant on next-morning driving performance in adult and elderly healthy volunteers. METHODS: Randomized, double-blind, double-dummy, placebo and active-controlled, four period incomplete crossover study in 48 healthy volunteers (22 females), 23-78 years old. Participants were treated at bedtime for eight consecutive nights with two of three dose levels of lemborexant (2.5, 5, or 10 mg), zopiclone 7.5 mg (on the first and last night with placebo on intervening nights), or placebo. Driving performance was assessed in the morning on days 2 and 9 using a standardized highway driving test in normal traffic, measuring standard deviation of lateral position (SDLP). Drug-placebo differences in SDLP >2.4 cm were considered to reflect clinically meaningful driving impairment. RESULTS: Mean drug-placebo differences in SDLP following lemborexant 2.5, 5, and 10 mg on days 2 and 9 were 0.74 cm or less. The upper bound of the 95% confidence intervals (CIs) for lemborexant treatment groups were all below 2.4 cm and the 95% CIs included zero, indicating that the effects were neither clinically meaningful nor statistically significant. Symmetry analysis further supported the lack of clinically meaningful impairment with lemborexant. CONCLUSIONS: When assessed starting ~9 h after lemborexant administration at bedtime the previous night, there was no statistically significant or clinically meaningful effect on driving performance in healthy adults and elderly, as assessed by either mean differences in SDLP relative to placebo or symmetry analysis. In this study, lemborexant at doses up to 10 mg was well-tolerated. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov, NCT02583451. https://clinicaltrials.gov/ct2/show/NCT02583451.

Lemborexant, A Dual Orexin Receptor Antagonist (DORA) for the Treatment of Insomnia Disorder: Results From a Bayesian, Adaptive, Randomized, Double-Blind, Placebo-Controlled Study.

STUDY OBJECTIVES: To identify dose(s) of lemborexant that maximize insomnia treatment efficacy while minimizing next-morning residual sleepiness and evaluate lemborexant effects on polysomnography (PSG) measures (sleep efficiency [SE], latency to persistent sleep [LPS], and wake after sleep onset [WASO]) at the beginning and end of treatment. METHODS: Adults and elderly subjects with insomnia disorder per the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition were enrolled in a multicenter, randomized, double-blind, placebo-controlled, Bayesian, adaptive, parallel-group study, receiving lemborexant (1, 2.5, 5, 10, 15, 25 mg) or placebo for 15 nights. Efficacy assessments included a utility function that combined efficacy (SE) and safety (residual morning sleepiness as measured by Karolinska Sleepiness Scale [KSS]), PSG measures, and sleep diary. Safety assessments included KSS, Digit Symbol Substitution Test, computerized reaction time tests, and adverse events (AEs). RESULTS: A total of 616 subjects were screened; 291 were randomized. Baseline characteristics were similar between lemborexant groups and placebo (∼63% female, median age: 49.0 years). The study was stopped for early success after the fifth interim analysis when the 15-mg dose met utility index/KSS criteria for success; 3 other doses also met the criteria. Compared with placebo, subjects showed significant improvements in SE, subjective SE, LPS, and subjective sleep onset latency at the beginning and end of treatment for lemborexant doses ≥ 5 mg (P < .05). WASO and subjective WASO showed numerically greater improvements for doses > 1 mg. AEs, mostly mild to moderate, included dose-related somnolence. CONCLUSIONS: Lemborexant doses ranging from 2.5-10 mg provided efficacy for the treatment of insomnia while minimizing next-morning residual sleepiness. CLINICAL TRIAL REGISTRATION: Title: A Multicenter, Randomized, Double-blind, Placebo-controlled, Parallel-group, Bayesian Adaptive Randomization Design, Dose Response Study of the Efficacy of E2006 in Adults and Elderly Subjects With Chronic Insomnia; URL: https://clinicaltrials.gov/ct2/show/NCT01995838; Identifier: NCT01995838.