The study will last 7 weeks, 5 of which will involve being on medication. You will take eszopiclone or placebo (sugar pill), keep a sleep diary and wear an actigraph, a device about the size of a digital watch that monitors and records sleep activity. You will randomly be chosen to get either placebo or medication. Half the subjects will get placebo and half eszopiclone. The decision will be made by a pharmacist (who does not know you) according to a randomization table. Neither you nor the investigating physician will know whether you are on sugar pill or medication. At both the beginning and the conclusion of the study you will be asked to fill out 2 questionnaires to evaluate fatigue and depression and undergo some memory and speech tests. The testing will take about 2 hours. Actigraphy is a wrist-worn, watch like device that records activity during waking and sleeping without application of any sensors. It consists of a movement detector, so it can record movement and non-movement data for a week or two. You should wear it continuously during wakefulness and sleep as you go about routine daily activities. You should only take it off if you are going to shower, bathe or swim. A sleep log is a graph on which, for 2 to 3 weeks, you will record bedtime, approximate sleep time, times and duration of awakenings during the sleep period, final awakening time, and naps taken during the day to the best of your knowledge. You will also be asked to avoid getting pregnant. If you are a woman who may have the potential to get pregnant then a pregnancy test may be performed at the beginning of the study, before you receive the medication, at the first follow up visit and when you end the study.