RecruitingBehavioural interventionBrief Behavioral Treatment for Insomnia in Veterans With Posttraumatic Stress DisorderThis study will investigate treatments for insomnia in Veterans who have posttraumatic stress disorder (PTSD). The purpose of this study is to compare a brief behavioral treatment for insomnia (BBTI) to a treatment that helps promote relaxation (progressive muscle relaxation training or PMRT). The investigators will examine improvements in psychosocial functioning and insomnia severity. The investigators will also examine whether treatment gains last over time and whether suicidal ideation decreases following insomnia treatment.