The purpose of this study is to evaluate the effect of Tibet Rhodiola Capsule on hypoxia and the cardiovascular risk factors in patients with mild to moderate OSA.

Inclusion Criteria:

1. Age >18 years, males or females;
2. HSAT or PSG testing within recent 3 months;
3. AHI 5-30 and lowest oxygen saturation<85%;
4. Refuse to accept CPAP, Mandibular orthosis device, surgery, or other medications to improve OSA;
5. Written informed consent.

Exclusion Criteria:

1. History of CPAP, Mandibular orthosis device, surgery, or other medications to improve OSA;
2. Significant central sleep apnea;
3. Histories of other sleep disorders: insomnia, chronic sleep deprivation, long-term use of sleeping pills or sedatives, restless legs syndrome;
4. Histories of underlying heart disease (cardiomyopathy, myocarditis, pericarditis or severe valvular disease), cardiogenic shock and heart failure (NYHA or Killip class 3-4), persistent atrial or ventricular arrhythmias;
5. History of myocardial infarction, coronary revascularization, and a known degree of stenosis > 75% of the coronary lesions;
6. Histories of known serious liver dysfunction (ALT or AST levels above 3 times the normal limit), renal insufficiency (GFR<30ml/min), moderate and severe chronic obstructive pulmonary disease, and pulmonary arterial hypertension;
7. Patients with malignant tumors, lymphoma and neuropsychiatric disorders;
8. Patients with major surgery or trauma within 3 months, and active bleeding or cerebrovascular accident within 6 months;
9. History of anemia (hemoglobin<90g/L) or thrombocytopenia (thrombocyte <90×10^9/L);
10. Breastfeeding, pregnant, or potentially fertile women;
11. Patients who have known to be allergic to Tibet Rhodiola Capsule or its components or patients with serious adverse effect;
12. Participation in other clinical trials in recent 3 months;
13. Patients who cannot complete this trial or comply with the protocol.