A Study of FK199B to Compare Efficacy With Zolpidem by Polysomnography in Patients With Insomnia

Inclusion Criteria: * Patient is diagnosed as a primary insomnia according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) * Patients complaining of insomnia continuously for 4 weeks or longer * Patient's usual bedtime is between 9 p.m. and 12 a.m. for the 4 week period prior to initial screening * Patient on most occasions sleeps for a total of ≥3 and \<6.5 hours over the 4 week period prior to initial screening * Patient's usual wake time after sleep onset in a single night is ≥45 minutes per night for the 4 week period prior to initial screening * Patients have a body weight of ≥45 kg and ≤85 kg, a BMI of ≥18.5 and \<30 Exclusion Criteria: * Patients with schizophrenia or manic-depressive psychosis * Patients with insomnia caused by physical diseases including chronic obstructive pulmonary disease, bronchial asthma, fibrositis syndrome, chronic fatigue syndrome, rheumatic disease, climacteric disturbance, and dermatitis atopic * Patients with circadian rhythm sleep disorder * Patient works night shifts * Patients with alcoholic sleep disorder * Patients with alcohol or drug dependence or a history of these * Patients with insomnia related with drugs including antiparkinson, antihypertensive, or steroid drugs * Patients with sleep apnea syndrome * Patients with restless legs syndrome or periodic limb movement disorder * Patients with epileptic insomnia * Patients smoke on average 40 or more cigarettes a day * Patients who had received psychotropic drugs other than hypnotics (including anxiolytic or antidepressant drugs for hypnotic effect) within a 4 week period prior to the initial screening