The proposed trial will examine the efficacy of telephone-delivered CBTi for alleviating sleep and non-sleep GWI symptoms in a two-arm randomized controlled trial. Veterans who have GWI and persistent insomnia disorder will be randomized to a group that will receive CBTi right away or to a group that will receive treatment-as-usual (i.e., the control group). Veterans randomized to the control group will have the option of receiving telephone-delivered CBTi upon completion of post-treatment assessments. The primary outcomes will be effect sizes base on within-group comparisons of pre-to-post-treatment change and maintenance of treatment effects at 6 months in the CBTi group.