A Study to Evaluate the Efficacy and Safety of Daridorexant in Participants With Insomnia Disorder

Inclusion Criteria:

• Signed informed consent prior to any study-mandated procedure;

• Male or female aged ≥ 19 years;

• Insomnia disorder according to DSM-5 criteria;

• The predominant complaint is dissatisfaction with sleep quantity or quality,associated with one (or more) of the following symptoms:

• Difficulty initiating sleep.

• Difficulty maintaining sleep (characterized by frequent awakenings or problemsreturning to sleep after awakenings).

• Early-morning awakening with inability to return to sleep.

• Insomnia Severity Index score ≥ 15;

• Insufficient sleep quantity as collected subjectively in the sleep diary A. ≥ 30 minto fall asleep, and B. Wake time during sleep ≥ 30 min, and C. Subjective TotalSleep Time (sTST) ≤ 6.5 h

Exclusion Criteria:

• Body mass index (BMI) ≥ 40.0 kg/m2

• Documented medical history and/or comorbidity of sleep-related breathing disorder

• History of and/or concurrent sleep apnea or suspected sleep apnea

• Korean-Mini Mental State Examination-2 (K-MMSE-2) score < 25 in subjects ≥ 50 years;

• For female subjects: pregnant, lactating or childbearing potential who do notconsent to true abstinence or use an effective method of contraception for requiredperiod

• Initiation of the cognitive behavior therapy (CBT) for treatment of insomniadisorder within 4 weeks prior to the Screening visit (Visit 1) or planned CBT duringthe study

• A history of moderate to severe hepatic impairment (eg, Child-Pugh Class B or C)

• Positive urine drug test or presence of alcohol in exhaled breath as detected bybreathalyzer test.