Insomnia is a serious health problem in Gulf War Veterans that is often associated with extensive prescription of sleeping medications. Although safer, even the latest "sleeping pills" can lead to cognitive impairment and risk of abuse. Thus non-pharmacological treatments for insomnia have been pursued as alternatives to medications. Cognitive Behavior Therapy for Insomnia (CBT-I) is the term widely used to describe therapies that combine behavioral and cognitive therapies for insomnia. The combined CBT-I approach has well-documented efficacy. Between 2012 and 2014 over 650 VA mental health clinicians have received extensive training in CBT-I. Although CBT-I is efficacious, the optimal target populations for its major components has not yet been well-defined for Gulf War Veterans. We propose to address this gap and develop tools for clinicians to identify the best treatment for insomnia for individual Gulf War Veterans.