Efficacy and Tolerability of Tasipimidine in Sleepless Patients

Inclusion Criteria: * Signed informed consent (IC) for participation in the study. * Male or female subjects with age between 18 and 65 years. * Insomnia disorder * Self-reported history of the following on at least 3 nights per week and for at least 3 months prior to the screening: ≥ 30 minutes to fall asleep, subjective total sleep time ≤ 6 hours. * Insomnia Severity Index© (ISI©) score ≥ 15 in Part 1 and ≥ 11 in Part 2. * Usual bedtime between 21:00 and 02:00. * Regular time in bed between 6 and 9 hours. * Meeting predefined sleep parameter criteria in sleep recording on the 2 screening nights. * Highly effective contraception. Exclusion Criteria: * Body mass index below 18.5 or above 40.0 kg/m2. * Daytime napping ≥ 1 hour per day, and ≥ 3 days per week. * Shift work within 2 weeks prior to the screening visit, or planned shift work during the study. * Travel across ≥ 3 time zones within 2 weeks prior to the screening visit, or planned travel across ≥ 3 time zones during the study. * Use of certain medications affecting central nervous system, e.g. sedatives or stimulans. * Start of other new chronic medication within 14 days prior screening nights and planned change to an ongoing chronic medication during the study. * Cognitive behavioural therapy (CBT) is allowed if the CBT started at least 1 month prior to the 1st screening night and the subject agreed to continue the CBT throughout the study. * Diagnosed sleep-related breathing disorder, including chronic obstructive pulmonary disease and sleep apnoea. * Acute or unstable psychiatric conditions. * Alcohol or substance use disorder within 2 years prior to the screening visit or inability to refrain from drinking alcohol for at least 3 consecutive days. * Significant cardiac disease. * Significant postural hypotension. * Heavy tobacco or other nicotine containing product use. * Caffeine consumption ≥ 600 mg per day or regular caffeine consumption after 4 p.m. * Heart rate \< 50 bpm or \> 100 bpm. * Systolic blood pressure \< 100 or \> 160 mmHg or diastolic blood pressure \< 50 or \> 100 mmHg * Abnormal 12-lead ECG finding. * Significant abnormal laboratory findings including positive drug screen and presence of alcohol in breath test. * Pre-planned elective surgery. * Pregnant or lactating females. * Blood donation or loss of significant amount of blood prior to the study. * Participation in a drug study within 60 days prior to the study. * Restless legs syndrome, circadian rhythm disorder, REM behaviour disorder, or narcolepsy.