The purpose of this study is to determine the dose response of Ramelteon, once daily (QD), in Japanese subjects with Chronic Insomnia

Complaints of sleep disorder are increasing with today's aging society and changing lifestyle. Sleep disorders not only impact one's activities of daily living, but also impede one's social life, leading to reduced productivity and sometimes accidents through carelessness.

Ramelteon is a melatonin-1 receptor agonist under global development by Takeda Chemical Industries, Ltd., Osaka, Japan, for the treatment of transient and chronic insomnia and for the treatment of Circadian Rhythm Sleep Disorders.

Inclusion Criteria:

• Has primary chronic insomnia for at least 3 months.
• Has a mean latency of greater than or equal to 20 minutes on 2 consecutive polysomnography screening nights with no night less than 15 minutes, and has a mean of at least 60 minutes of wake time across 2 nights with no night less than 45 minutes.
• Has a habitual bedtime between 8:30 PM and 12:00 AM.
• Has a body mass index that is not less than 17, but less than 34.
• Females of childbearing potential who are sexually active must agree to use a medically accepted means of contraception, and can neither be pregnant nor lactating from Screening throughout the duration of the study.

Exclusion Criteria:

• Has a history of psychiatric disorder (including depression and anxiety), seizures, drug addiction, sleep apnea, nocturnal myoclonus and/or mental retardation as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition.
• Has a history of alcohol abuse within the previous 2 years.
• Has a hepatic disease, and a significant neurological, renal, endocrine, cardiovascular, gastrointestinal, pulmonary, hematological or metabolic disease.
• Has a known hypersensitivity to ramelteon or related compounds, including melatonin.
• Has a positive hepatitis panel including hepatitis A, hepatitis B or hepatitis C.
• Has any clinically abnormal findings as determined by a medical history, physical examination, electrocardiogram or clinical laboratory tests by the investigator or sub investigator.
• Has experienced 3 hours or more of jet lag within 7 days preceding the polysomnography screening.
• Has an apnea-hypopnea index (per hour of sleep) greater than or equal to 10 as seen on the first night of polysomnography screening.
• Has periodic limb movement with arousal index (per hour o sleep) greater than or equal to 10 as seen on the first night of polysomnography screening.
• Has participated in an excessive weight loss program that may have given influence on the evaluation of this study, or altered the participant's exercise routine within 30 days prior to double-blind study medication administration.
• Has had a clinically significant illness within 30 days prior to double-blind study medication administration.
• Has had sleep schedule changes required by employment (e.g., shift worker) within 3 months prior to double-blind study medication administration.
• The investigator or sub investigator judges the study subject inappropriate for participation because it is considered difficult to complete the study, or participating in the study will not be in the best interest of the subject.