A trial randomly assigned 107 patients with chronic insomnia to receive 4 mg, 8 mg, 16 mg, and then 32 mg of ramelteon sequentially, followed by placebo with a washout period of 5 to 12 days between each treatment. The treatment was administered 30 minutes prior to the patient's usual bedtime. All doses of ramelteon decreased sleep onset latency by 10 to 15 minutes and increased total sleep time by 10 to 15 minutes without adverse effects, as measured by polysomnography.