This study aims to evaluate the effectiveness and safety of lemborexant (a new dual orexin receptor antagonist) in the treatment of patients with mental disorders complicated with insomnia. The subjects are patients aged 18 years and above, who meet the DSM-5 diagnostic criteria for mental disorders and have an Insomnia Severity Index (ISI) score ≥11. They will receive lemborexant treatment for 8 weeks, with follow-up to observe the improvement of insomnia symptoms and adverse events, so as to provide real-world evidence for the clinical optimization of treatment regimens for insomnia comorbid with psychiatric disorders.

Background: The incidence of insomnia in patients with psychiatric disorder is as high as 70%-80%. Traditional benzodiazepine receptor agonists have risks such as addiction and cognitive impairment. Lemborexant was approved for marketing in China in 2025, but its real-world data in the population with insomnia comorbid with psychiatric disorder is insufficient. Hypothesis: 8-week treatment with lemborexant can significantly improve insomnia symptoms in insomnia comorbid with psychiatric disorders, with good safety. Design: A multicenter, prospective, single-arm, observational study. It is planned to enroll 121 patients (with an expected dropout rate of 30%), who will receive 8-week treatment. Efficacy will be evaluated by scales such as ISI and VAS, and adverse events will be monitored.

Inclusion Criteria:

1. Aged 18 years and above, regardless of gender;
2. Meet the DSM-5 diagnostic criteria for mental disorders (any type);
3. Insomnia Severity Index (ISI) score ≥11;
4. Have at least 7 hours of sleep time available;
5. Able to complete the 2-month scale assessment and follow-up plan;
6. Voluntarily sign the informed consent form;
7. Intend to receive lemborexant treatment as judged by the clinicians

Exclusion Criteria:

1. Mental disorder is in the acute phase as judged by clinical assessment, or the dose of other psychotropic drugs cannot be stabilized during the study;
2. Concurrent use of ≥2 types of benzodiazepine receptor agonists (BZRAs) as insomnia treatment drugs;
3. Previous continuous use of dual orexin receptor antagonist (DORA)-type drugs for >1 week;
4. Clear suicide attempt/plan or high suicide risk as judged by the researcher;
5. Pregnant or lactating women;
6. Patients with narcolepsy;
7. Patients with severe hepatic insufficiency;
8. Currently accompanied by severe or unstable diseases of cardiovascular, respiratory, digestive and other systems;
9. Other conditions deemed unsuitable for participation by the researcher

Adults ≥18 years with any DSM-5-diagnosed mental disorder, ISI score ≥11, ≥7 hours available sleep time, ability to complete 2-month assessments/follow-up, voluntary informed consent, and clinical indication for lemborexant treatment.