• Total sleep time (TST) as recorded in patient diaries [ Time Frame: week 12 ] [ Designated as safety issue: No ]
  

• Wake time after sleep onset (WASO) [ Time Frame: week 12 ] [ Designated as safety issue: No ]
  
• Sleep quality [ Time Frame: week 12 ] [ Designated as safety issue: No ]
  
• Clinician-rated overall severity of fibromyalgia [ Time Frame: week 12 ] [ Designated as safety issue: No ]
  
• Fibromyalgia Impact Questionnaire [ Time Frame: week 12 ] [ Designated as safety issue: No ]
  

Fibromyalgia (FM) is a prevalent, debilitating, and costly syndrome. Although the pathophysiology of FM is not yet well-understood, sleep disturbance is a prominent feature of most theories. Eszopiclone has been approved by the FDA for the treatment of insomnia, but has not been studied in the treatment of FMS. The purpose is to assess the efficacy of eszopiclone for the treatment of insomnia and other symptoms of fibromyalgia (FMS) in FMS patients. Participants will be randomly selected to receive eszopiclone or placebo. It is hypothesized that participants receiving eszopiclone will report greater improvement in total sleep time, sleep quality, pain, fatigue, physical functioning, and emotional distress than will those receiving placebo.

Inclusion Criteria:

1. Male or female, age 18 through 64.
2. Meets ACR criteria for FMS, as determined by rheumatological examination and a medical history review.
3. Reports sleep maintenance insomnia (total sleep time of < 6.5 hours or sleep impairment consisting of 3 of 7 nights per week for a month by history) or sleep onset latency insomnia (at least 3 of 7 nights of sleep latency > 30 minutes), as well as clinically significant daytime distress or impairment during the 1 week self assessment prior to baseline.
4. Has completed 8th grade and is fluent in English.
5. If a female of child bearing potential, the patient must be non-pregnant and either post-menopausal or using an approved birth control method. Acceptable birth control methods include: history of tubal ligation, having a male partner who is sterile, IUDs, birth control pills or other hormonal birth control methods (e.g., birth control patch, Depo-Provera injections), and double-barrier methods (e.g., condom and foam).
6. Antidepressant medication will be allowed if the patient has been on a stable dose for at least one month.

Exclusion Criteria:

1. Evidence of traumatic injury, inflammatory rheumatic disease, or infectious or endocrine-related arthropathy.
2. Evidence of a primary sleep disorder (e.g., significant sleep disordered breathing (central or obstructive apnea), periodic limb movement disorder, or REM sleep behavior disorder.
3. Any current, clinically significant medical condition.
4. Pregnancy.
5. Meets DSM-IV criteria for bipolar disorder, psychotic disorder, organic brain syndrome, or psychoactive substance abuse or dependence.
6. Any current psychiatric disorder that would interfere with study participation (investigator judgment).
7. Active suicidal ideation.
8. Plans to engage in additional psychotherapy during the study.
9. Concurrent use of benzodiazepines after 6pm or as a sleep aid.
10. Concurrent use of any other sleep aid.
11. Concurrent use of analgesics other than acetaminophen or non-steroidal anti-inflammatory medication.
12. Concurrent use of any medication that has not been stabilized for at least 1 month prior to screening.