Outpatients with chronic insomnia who participate in this study will be treated in each of four 2-week treatment periods with bedtime doses of either placebo, zolpidem, LY2624803 1 mg, or LY2624803 3 mg. Neither patients nor investigators will be told what treatments are being given in any treatment period. A patient who completes all four treatment periods will be treated with placebo in 1, 2, or 3 of the periods; with zolpidem in 0, 1, or 2 of the periods; and with LY2624803 in either 1 or 2 of the periods. No patient will receive placebo for all four of the 2-week treatment periods. All patients will receive LY2624803 for at least one of the four 2-week treatment periods. During each treatment period, patients will record information each morning about their sleep the night before, and each evening about their functioning since waking up. Patients will also wear wrist actigraphy devices to record their physical activity. At the conclusion of each treatment period, patients will answer questions about their sleep, functioning, health, and relative preference for treatments.