The Study of Combination Use of Melatonin Receptor Agonist for Dose Reduction or Interruptions of Benzodiazepine (BZD) and Non-BZD Hypnotics on Chronic Insomnia

Inclusion Criteria: Subjects meeting Criteria 1 or 2 and Criteria 3 and all subsequent criteria will be included in the study: 1. Patients diagnosed as chronic insomnia having sleep onset disturbance, and with a duration of the disease of at least 6 months 2. Patients diagnosed with chronic insomnia comorbid with mood disorders (depression or bipolar disorder) can be included to this study if they have remission of mood symptoms. 3. Patients taking (non-)BZD hypnotics (including etizolam at bedtime) at a fixed dose in the following patterns since at least 1 month prior to consent (over 90% of drug compliance should be confirmed at the time of medical interview): * Patients taking 2 drugs at the usual dose (1 unit) * Patients taking 3 drugs at the usual dose (1 unit) * Patients taking 4 drugs at the usual dose (1 unit) * Patients taking a drug at 2-fold of the usual dose (2 units) * Patients taking a drug at 2-fold of the usual dose (2 units) and a drug at the usual dose (1 unit) * Patients taking a drug at 2-fold of the usual dose (2 units) and 2 drugs at the usual dose (1 unit) * Patients taking 2 drugs at 2-fold of the usual dose (2 units) Patients whose total dosage are 2～4 units of 1～4 drugs can be also included. But attention needed not to conflict with exclusion criteria 2. ※Dosage cannot exceeded 2 units per 1 drug. * Patients whose symptoms of insomnia were stabilized, and the investigators determined that the (non-) BZD hypnotics could be reduced or discontinued * Patients aged 20 years or older at the time of consent * Patients who are willing to comply with algorithm for dose reduction and discontinuation * Patients who can understand the content of the study and provide consent to participate in the study in writing on their own will. Exclusion Criteria: Subjects meeting any of the following criteria will not be included in the study: * Patients with secondary insomnia * Patients taking (non-)BZD hypnotics at a dose exceeding 2-fold of the usual dose * Patients taking barbiturate and non-barbiturate hypnotics and Suvorexant. * Patients taking hypnotics other than medicinal pharmaceuticals (including Over The Counter (OTC), supplements believed to be effective for insomnia and melatonin ) * Patients taking mianserin hydrochloride, mirtazapine, and trazodone hydrochloride * Patients taking antipsychotics * Patients taking anxiolytic or clonazepam at bedtime \*Patient taking anxiolytic and/or clonazepam at times except for bed-time will be included in the study. However, dosage and timing of administration can not be changed during the study period. * Patients who took ramelteon within 1 month prior to the informed consent * Patients in whom the dose of psychotropics except for the items 2～7 were changed within 1 month prior to the informed consent * Patients who are comorbid with depression or bipolar disordered and in whom depressive symptoms have not remitted * Patients in whom frequency in Q9 of PHQ "thoughts that you would be better off dead or thoughts of hurting yourself in some way" is "more than half the days (in the past 2 weeks)" or the total score is 10 or higher * Patients with dementia, schizophrenia, drug dependence and alcoholic * Patients with liver/kidney disorder, female subjects who are pregnant or in breast-feeding, and malignant neoplasm * Night workers * Patients meeting contraindications for ramelteon * Other patients judged ineligible for participation in the study by the investigator