Please assess the completion status of the following clinical trial:

Trial Title: Impact of Dexmedetomidine on Sleep Quality

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: PHASE4
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion Criteria:~1. Age \>= 65 years~2. Scheduled to undergo elective non-cardiac major surgery (with expected duration \>= 2 hours) under general anesthesia~3. Transferred to general ward with a patient-controlled intravenous analgesia pump after surgery.~Exclusion Criteria:~1. Refuse to participate~2. Preoperative history of schizophrenia, epilepsy, parkinsonism or myasthenia gravis~3. Patients with preoperative sleep disorders (accepted sedatives or hypnotics within 1 month before surgery) or the STOP-BANG Questionnaire score is 3 or higher~4. Inability to communicate in the preoperative period because of coma, profound dementia or language barrier~5. Brain injury or neurosurgery~6. Preoperative left ventricular ejection fraction \< 30%, sick sinus syndrome, severe sinus bradycardia (\< 50 beats per minute), or second-degree or above atrioventricular block without pacemaker~7. Severe hepatic dysfunction (Child-Pugh class C); Severe renal dysfunction (requirement of renal replacement therapy before surgery); ASA classification IV or unlikely to survive for more than 24 hours after surgery~8. Patients recruited in other studies~9. Other conditions that are considered unsuitable for study participation

- Gender: ALL
- Minimum Age: 65 Years
- Maximum Age: 90 Years
- Healthy Volunteers: f

Study Arms:
- Dexmedetomidine group (Type: EXPERIMENTAL): Morphine (0.5 mg/ml, in a total volume of 160 ml) is used for patient-controlled analgesia. Dexmedetomidine (200 ug) is added to the formula of patient-controlled analgesia. Patient-controlled analgesia is provided during the first 3 days after surgery.
- Placebo group (Type: PLACEBO_COMPARATOR): Morphine (0.5 mg/ml, in a total volume of 160 ml) is used for patient-controlled analgesia. Placebo (normal saline) is added to the formula of patient-controlled analgesia. Patient-controlled analgesia is provided during the first 3 days after surgery.

Based on this trial design, predict the completion outcome and termination type (if applicable).