Eligibility Criteria:
Inclusion Criteria:
For inclusion in the study patients must fulfil all of the following criteria:
1. Provision of written informed consent by patient or his/her legal guardian
2. Hospitalised for a diagnosis of major depressive disorder by DSM-IV (296.2X, 296.3X)
3. HRSD score\>18
4. Total score of sleep disturbance factor in HRSD (items 4, 5, and 6; score range, 0-6)\>3
5. Females or males, and aged 18 to 65 years
6. Able to understand and comply with the requirements of the study
Exclusion Criteria:
Any of the following is regarded as a criterion for exclusion from the study:
1. Pregnancy or lactation
2. Any DSM-IV Axis I disorder, except for major depressive disorder
3. Patients who, in the opinion of the investigator, pose an imminent risk of suicide or a danger to self or others
4. Known intolerance or lack of response to sertraline, as judged by the investigator
5. Use of any of the following cytochrome P450 3A4 inhibitors in the 14 days preceding enrolment including but not limited to: ketoconazole, itraconazole, fluconazole, erythromycin, clarithromycin, troleandomycin, indinavir, nelfinavir, ritonavir, fluvoxamine and saquinavir
6. Use of any of the following cytochrome P450 3A4 inducers in the 14 days preceding enrolment including but not limited to: phenytoin, carbamazepine, barbiturates, rifampin, St. John's Wort, and glucocorticoids
7. Administration of a depot antipsychotic injection within one dosing interval (for the depot) before randomisation
8. Substance or alcohol dependence at enrolment (except dependence in full remission, and except for caffeine or nicotine dependence), as defined by DSM-IV criteria
9. Opiates, amphetamine, barbiturate, cocaine, cannabis, or hallucinogen abuse by DSM-IV criteria within 4 weeks prior to enrolment
10. Medical conditions that would affect absorption, distribution, metabolism, or excretion of study treatment
11. Unstable or inadequately treated medical illness (e.g. congestive heart failure, angina pectoris, hypertension) as judged by the investigator
12. Organic change was founded by brain CT
13. Involvement in the planning and conduct of the study
14. Previous enrolment or randomisation of treatment in the present study
15. Participation in another drug trial within 4 weeks prior enrolment into this study or longer in accordance with local requirements
16. An absolute neutrophil count (ANC) of 1.5 x 109/L
17. Sleep disorder such as Apnea and Hyponea Syndrome, PLMS and narcolepsy
18. The work time is rotate and/or often flies across the time zone
19. Concomitant use in patients taking monoamine oxidase inhibitors (MAOIs)
20. Concomitant use in patients taking pimozide