A multicenter, randomized, double-blind, placebo-controlled, parallel-group study of eszopiclone 3 mg in women with insomnia secondary to perimenopause or menopause. Eligible subjects will be randomized to either eszopiclone 3 mg or placebo nightly for four weeks. This study was previously posted by Sepracor Inc. In October 2009, Sepracor Inc. was acquired by Dainippon Sumitomo Pharma., and in October 2010, Sepracor Inc's name was changed to Sunovion Pharmaceuticals Inc.