To determine the safety and efficacy of eszopiclone as adjunctive therapy in the treatment of insomnia in patients with insomnia related to Generalized Anxiety Disorder. All subjects will receive an approved anxiolytic agent and will be randomized to nightly therapy with either eszopiclone or placebo.

An 8-week, randomized, double-blind, placebo-controlled, parallel-group adjunctive therapy trial. The study consists of subjects with insomnia related to Generalized Anxiety Disorder who will be treated for 10 weeks with open-label escitalopram oxalate 10 mg/day at bedtime, and randomized to receive either eszopiclone 3 mg nightly or placebo nightly for 8 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.

• Subjects, between the ages of 18 and 64 years inclusive
• Subjects with Generalized Anxiety Disorder (GAD)
• Subjects with insomnia related to GAD.