To evaluate 6 months' eszopiclone treatment upon patient-reported sleep, fatigue and sleepiness, insomnia severity, quality of life, and work limitations. Randomized, double blind, controlled clinical trial. 54 research sites in the U.S. 830 primary insomnia patients who reported mean nightly total sleep time (TST) < or = 6.5 hours/night and/or mean nightly sleep latency (SL) >30 min. Eszopiclone 3 mg or matching placebo. Patient-reported sleep measures, Insomnia Severity Index, Medical Outcomes Study Short-Form Health Survey (SF-36), Work Limitations Questionnaire, and other assessments measured during baseline, treatment Months 1-6, and 2 weeks following discontinuation of treatment. Patient-reported sleep and daytime function were improved more with eszopiclone than with placebo at all months (P <0.001). Eszopiclone reduced Insomnia Severity Index scores to below clinically meaningful levels for 50% of patients (vs 19% with placebo; P <0.05) at Month 6. SF-36 domains of Physical Functioning, Vitality, and Social Functioning were improved with eszopiclone vs placebo for the Month 1-6 average (P < 0.05). Similarly, improvements were observed for all domains of the Work Limitations Questionnaire with eszopiclone vs placebo for the Month 1-6 average (P <0.05). This is the first placebo-controlled investigation to demonstrate that long-term nightly pharmacologic treatment of primary insomnia with any hypnotic enhanced quality of life, reduced work limitations, and reduced global insomnia severity, in addition to improving patient-reported sleep variables.