Inclusion Criteria:

1. Subjects must be 18 to 65 years of age, inclusive.
2. Subjects must have lifetime bipolar I disorder as defined by DSM-IV-TR criteria.
3. Subjects' manic symptoms must be mild to moderate in severity, defined as an YMRS score between 10 and 25.
4. Subjects must be currently experiencing a clinically significant sleep disturbance, defined as a PSQI total score > 5.
5. Subjects must be receiving at least 1 mood stabilizing medication, which may include an atypical antipsychotic (e.g., aripiprazole, clozapine, olanzapine, quetiapine, risperidone, ziprasidone) and/or mood stabilizer/anticonvulsant (e.g, lithium, carbamazepine, valproate/divalproex, lamotrigine, oxcarbazepine) medication for > 1 week prior to baseline. Continued administration of benzodiazepines or sedative-hypnotics will be allowed only if the subject has been receiving the medication for > 2 weeks prior to baseline.
6. Subjects or their legally authorized representative must sign the Informed Consent Document after the nature of the trial has been fully explained.
7. If female, subjects must be: postmenopausal, surgically incapable of childbearing, or practicing medically acceptable effective method(s) of contraception (e.g., hormonal methods, barrier methods, intrauterine device) for at least 1 month prior to study entry and throughout the study.

Exclusion Criteria:

1. Subjects who are experiencing clinically significant suicidal or homicidal ideation.
2. Subjects who are currently experiencing psychotic symptoms.
3. Subjects with a current DSM-IV-TR Axis I diagnosis of delirium, dementia, amnesia, or other cognitive disorders; a DSM-IV-TR diagnosis of a substance dependence disorder within the past 6 months; or, a lifetime DSM-IV-TR psychotic disorder (e.g., schizophrenia or schizoaffective disorder).
4. Subjects with serious general medical illnesses including hepatic, renal, respiratory, cardiovascular, endocrine, neurologic, or hematologic disease as determined by the clinical judgment of the investigator.
5. Subjects with hypo- or hyperthyroidism unless stabilized on thyroid replacement for > 3 months.
6. Subjects with a clinically significant abnormality in their pre-study physical exam, vital signs, EKG, or laboratory studies.
7. Subjects who are allergic to or who have demonstrated hypersensitivity to ramelteon.
8. Subjects who are taking medications that interact with ramelteon (e.g., ketoconazole, fluconazole, fluvoxamine, rifampin).
9. Females who are pregnant or nursing.
10. Subjects who have received an experimental drug or used an experimental device within 30 days.