Inclusion Criteria

• Male or a post-menopausal female.
• Primary insomnia as defined by the Diagnostic and Statistical Manual of Mental Disorders, Text Revision for at least 3 months and as defined by subjective sleep latency greater than or equal to 30 minutes, subjective total sleep time less than or equal to 6.5 hours per night, and daytime complaint(s) associated with disturbed sleep.
• Mean latency of greater than or equal to 20 minutes per polysomnography on two consecutive screening nights with neither night less than 15 minutes. Also, a mean of 60 minutes of wake time during the 480 minutes in bed across two nights with no night less than 45 minutes.
• Habitual bedtime is between 8:30 p.m. and 12:00 a.m.
• 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 Day 1 of single-blind study medication, whichever is longer.
• Sleep schedule changes required by employment (eg, shift worker) within three months prior to Day 1 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 Day 1 of single-blind study medication.
• Ever had a history of seizures, sleep apnea, chronic obstructive pulmonary disease, 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.
• Had an acute clinically significant illness, as determined by the investigator, within 30 days prior to Day 1 of single-blind study medication.
• Current significant neurological (including cognitive and psychiatric disorders), hepatic, renal, endocrine, cardiovascular, gastrointestinal, pulmonary, hematologic, or metabolic disease, unless currently controlled and stable with protocol-allowed medication 30 days prior to Day 1 of single-blind study medication.
• Used tobacco products within 90 days prior to Day 1 of single-blind study medication.
• Used melatonin, or other drugs or supplements known to affect sleep/wake function, or has consumed grapefruit or grapefruit juice within 5 days (or 5 half lives, whichever is longer) prior to Day 1 of single-blind study medication.
• Used any central nervous system medication within 3 weeks (or 5 half lives of the drug, whichever is longer) prior to Day 1 of singleblind study medication. These medications must not have been used to treat psychiatric disorders.
• 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 including anti-hepatitis A virus (only immunoglobulin M is exclusionary), anti- hepatitis B surface (except in subjects who have received hepatitis B virus vaccination), hepatitis B surface antigen, anti- hepatitis B core (only immunoglobulin M is exclusionary), or anti-hepatitis C virus.
• Positive urine drug screen including alcohol at screening and each check-in or a positive breathalyzer test at each check-in.
• Apnea hypopnea index (per hour of sleep) greater than 15 as seen on polysonography, on the first night of the polysonography screening.
• Periodic leg movement with arousal index (per hour of sleep) greater than 20 as seen on polysonography, on the first night of polysonography screening.
• Any additional condition(s) that in the Investigator.s opinion would: a) affect sleep/wake function, b) prohibit the subject from completing the study, or c) not be in the best interest of the subject to participate in the study.

• 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:

  • Within 3 weeks prior to Day 1 of single-blind study medication and during the study:

    • anxiolytics
    • hypnotics
    • antidepressants
    • anticonvulsants
    • sedating H1 antihistamines
    • systemic steroids
    • respiratory stimulants (eg, theophylline) 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
    • St. John.s wort
    • kava-kava
    • gingko biloba, any other supplements

  • Within 5 days prior to Day 1 of single-blind study medication and during the study:

    • melatonin, or other drugs or supplements known to affect sleep/wake function.