One aspect of the present invention relates to pharmaceutical compositions containing two or more active agents that when taken together can be used to treat, e.g., insomnia and/or depression. The first component of the pharmaceutical composition is a GABA receptor modulating compound. The second component of the pharmaceutical composition is a serotonin reuptake inhibitor, a norepinephrine reuptake inhibitor, a 5-HT2A modulator, or dopamine reuptake inhibitor. In certain embodiments, the pharmaceutical composition comprises eszopiclone. In a preferred embodiment, the pharmaceutical composition comprises eszopiclone and fluoxetine. The present invention also relates to a method of treating a sleep abnormality, treating insomnia, treating depression, augmenting antidepressant therapy, eliciting a dose-sparing effect, reducing depression relapse, improving the efficacy of antidepressant therapy or improving the tolerability of antidepressant therapy, comprising co-administering to a patient in need thereof a GABA-receptor-modulating compound; and a SRI, NRI, 5-HT2A modulator or DRI.