The main purpose of this study is to evaluate the efficacy and safety of YZJ-1139 in the short-term treatment of primary chronic insomnia, explore the optimal effective dose, and provide the basis for phase III clinical trials

Inclusion Criteria:

1. Aged ≥ 18 to < 65 years.
2. Meet the clinical diagnostic criteria for primary chronic insomnia disorder as defined in ICSD-3 criteria.
3. PSG results for 2 consecutive nights during the run-in period should meet the following conditions:

1) The mean LPS of 2 nights is ≥ 30 min, with the LPS ≥ 15 min for any night; 2) And/or the mean WASO of 2 nights is ≥ 30 min, with neither night ≥20 min; 3) The mean SE of 2 nights is ≤ 85%, with the SE ≤ 87.5% for both nights. 4. During the study, the patient agreed to follow the daily bedtime between 9 and 12 pm , stayed in bed for 6.5-9 hours every night, and agreed to refrain from taking a nap.

5. Female subjects are confirmed to be non-pregnant at screening; both men of reproductive potential and women of childbearing potential should agree to use medically acceptable and effective contraception throughout the study and within 1 month after the end of the study.

6. Understand the study procedures and contents, voluntarily participate in the clinical study and sign the written Informed Consent Form (ICF), have good compliance during participation in the study, and are willing to attend the visits

Exclusion Criteria:

1. Sleep disorders associated with neurological disorders such as depression, anxiety, sleep disorders due to dementia; depression: Hamilton Depression Scale (HAMD) score ≥ 18 or item 3 (suicidal ideation) score of 3 or more; anxiety: Hamilton Anxiety Scale (HAMA) score ≥ 14; dementia: MMSE scale score ≤ 20 for primary school, ≤ 22 for secondary school (including technical secondary school), and ≤ 23 for college (including junior college).
2. Apnea-hypopnea index [AHI] and/or periodic limb movement index [PLMI] > 10 times/hour detected by PSG monitoring during the run-in period.
3. Patients with severe endocrine diseases, blood diseases, cardiovascular and cerebrovascular diseases, autoimmune diseases, respiratory function impairment and other related diseases.
4. Previous history of nervous system disorders such as epilepsy, schizophrenia, bipolar mental disorder, neurodevelopmental retardation, cognitive disorder, narcolepsy, and restless leg syndrome.
5. Receiving any hypnotics, antidepressants, antipsychotics, anticholinergics, memory-enhancing drugs, antihistamines, CYP3A inducers, CYP3A inhibitors within 2 weeks prior to the start of the lead-in PSG.
6. History of drug taking or addiction, which is known through questioning.
7. Have any lifestyle that interferes with the study process or may interfere with sleep: for example, there will be travels across zones within the next 2 weeks or during the study period, or there will be shift work (night and daytime shift).etc.
8. Special occupants who need to operate machinery during the test period, such as professional drivers, high-altitude operators, etc.
9. Subjects who were treated with any other approved or investigational insomnia medication prior to the study, including other orexin receptor inhibitors, or specific herbal preparations, traditional Chinese medicines, and still needed to continue in the study.
10. AST and ALT > 2 × the upper limit of normal (ULN), or Cr > 1.5 × ULN, or white blood cells < lower limit of normal.
11. Hyperthyroidism or hypothyroidism.
12. History of alcohol abuse (defined as regular daily alcohol consumption exceeding the following criteria: approximately 720 mL of beer, or 240 mL of wine, or 60 mL of liquor).
13. History of drug abuse , or positive urine drug screening (screening and/or baseline) for any indicator.
14. Regular daily consumption of excessive tea and coffee drinks.
15. Patients who have participated in other drug clinical trials within the past 3 months, or participated in other research trials during this trial.
16. Pregnant or lactating women.
17. History of allergy to the investigational product or its components.
18. Have other conditions that make the subject unsuitable for participation in the clinical study in the opinion of the investigator.