A double-blind, randomized, placebo controlled, parallel group study of eszopiclone in elderly subjects with primary chronic insomnia. The study will involve up to 9 visits and subject participation will be approximately 18 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.