To Compare the Effectiveness of Suvorexant vs Placebo on Sleep Pressure in Hypertensives With Insomnia

Inclusion Criteria: \[At interim registration\] Patients who meet the following criteria are eligible for the study: 1. Patients who give written consent of agreement to voluntarily participation in the clinical study 2. Age 20 years or older 3. Sex: Male or female 4. Treatment classification: Outpatient 5. Hypertensive patient who meet at least one of the following: * Under antihypertensive medications * Clinic systolic blood pressure (SBP) less than 160 mmHg 6. Patients with insomnia who meet at least one of the following: * Patients with any one of the following symptoms twice a week or more and at least 1 month-continuation: difficulty initiating sleep (time to sleep onset 2 hours or more longer than usual), difficulty maintaining sleep (awakening twice or more in the night), early morning awakening (awakening 2 hours or more earlier in the morning than usual), difficulty sleeping deeply (no soundly asleep feeling at the time of awakening in the morning). b. Patients with interference with social or occupational function due to the above insomnia symptoms \[At official registration\] Patients who meet the following criteria at the end of run-in period are eligible for the study: 1. Stable unchanged antihypertensive medication for run-in period. 2. Average morning home SBP more than 135 mmHg during 5 days before the end of run-in period. Exclusion Criteria: 1. Patients with serious liver disease. 2. Patients with serious respiratory disease. 3. Patients with secondary hypertension 4. Patients with sleep apnea syndrome 5. Patients with history of narcolepsy or cataplexy 6. Patients with history of organic cerebral disorders 7. Patients with history of hypersensitivity to suvorexant 8. Patients received CYP3A strongly-inhibitors including itraconazole, clarithromycin and ritonavir, saquinavir, nelfinavir, indinavir, telaprevir and voriconazole at the start of the run-in period 9. Patients with average clinic SBP of 160 mmHg or more at the start of the run-in period 10. Patients received suvorexant and other hypnotic at the start of the run-in period on a regular basis 11. Patients who are breast-feeding, pregnant, possibly pregnant, or plan to become pregnant 12. Patients who are considered not to be eligible for this study by their investigator or sub-investigator