Ramelteon in Adults With Chronic Insomnia

Inclusion Criteria * Females of childbearing potential who are sexually active must agree to use adequate contraception, and can neither be pregnant nor lactating from Screening throughout the duration of the study. * Has had primary insomnia as defined by the Diagnostic and Statistical Manual of Mental Disorders, Text Revision and a history of daytime complaint(s) associated with disturbed sleep. * Subjective sleep latency greater than or equal to 45 minutes and a subjective total sleep time less than or equal to 6.5 hours per night for at least 3 nights during the week of the lead-in period, based on subject diary. * Habitual bedtime is between 8:30 PM and 12:00 AM. * Body mass index between 18 and 34, inclusive. Exclusion Criteria * Known hypersensitivity to Ramelteon or related compounds, including melatonin. * Previously participated in a study involving Ramelteon. * Participated in any other investigational study, and/or taken any investigational drug within 30 days or five half-lives prior to the first day of single-blind study medication, whichever is longer. * Sleep schedule changes required by employment (eg, shift worker) within three months prior to the first day of single-blind study medication, or has flown across greater than three time zones within seven days prior to screening. * Participated in a weight loss program or has substantially altered their exercise routine within 30 days prior to the first day of single-blind study medication. * Has ever had a history of seizures, sleep apnea, chronic obstructive pulmonary disease, restless leg syndrome, schizophrenia, bipolar disorder, mental retardation, or cognitive disorder. * History of psychiatric disorder (including anxiety or depression) within the past 12 months. * History of drug addiction or drug abuse within the past 12 months. * History of alcohol abuse within the past 12 months. * Current significant neurological, hepatic, renal, endocrine, cardiovascular, gastrointestinal, pulmonary, hematologic or metabolic disease unless currently controlled and stable with protocol-allowed medication 30 days prior to the first day of single-blind study medication. * Uses tobacco products during nightly awakenings. * Any clinically important abnormal finding as determined by a medical history, physical examination, electrocardiogram, or clinical laboratory tests, as determined by the investigator. * Positive hepatitis panel. * Any additional condition that in the Investigator's opinion would: * Affect sleep-wake function * Prohibit the subject from completing the study * Not be in the best interest of the subject. * Is required to take or continues taking any disallowed medication, prescription medication, herbal treatment or over-the counter medication that may interfere with evaluation of the study medication, including: * melatonin or other drugs or supplements known to affect sleep/wake function. * anxiolytics * hypnotics * antidepressants * anticonvulsants * sedating H1 antihistamines * systemic steroids * respiratory stimulants and decongestants * over-the-counter and prescription stimulants * over-the-counter and prescription diet aids * central nervous system active drugs (including herbal preparations with central nervous system effects) * narcotic analgesics * beta blockers * melatonin * St. John's Wort * kava-kava * gingko biloba