This research was designed to examine the causes and consequences of sleep problems among servicemembers and to identify promising policy options for the U.S. Department of Defense (DoD) to mitigate the negative consequences of sleep problems and to promote sleep health. Although sleep is an issue throughout the deployment cycle, we focus in particular on the post-deployment period because of an increased awareness that this period may be one of particular risk for chronic sleep problems and downstream mental and physical health consequences. However, policies and programs are not specifically tied to post-deployment, so we expanded the scope of our literature and policy reviews.
To achieve our overall research objective, in collaboration with the sponsor, the RAND team designed a multidimensional research project addressing five research questions, as shown in Figure 1.1.
Figure 1.1. Research Questions to Examine Sleep in the Military
To address these questions, the study team used five complementary methods: (1) a literature review, (2) primary data collection and analysis of a sleep survey, (3) a policy review, (4) key informant interviews, and (5) working group discussions with invited experts. Each method is described briefly in the following sections and in more detail in later chapters in this report. Table 1.1 provides a crosswalk between the five research questions and the methods used to address each question. Given the variation of sleep terminology used in the literature on military sleep, and to help guide the reader throughout this report, we include definitions of commonly used sleep terms in Appendix A.
We conducted two literature reviews—one on the prevalence and consequences of sleep problems in servicemember populations in the post-deployment period (Chapter Two) and another on evidence-based practices to treat sleep disorders in servicemember populations (Chapter Four). To locate articles for the literature review, we performed comprehensive Internet searches on a broad range of search terms related to the project's research questions, using multiple databases (e.g., PubMed, Psyclnfo). We also searched for "gray literature" using the WorldCat database, which indexes books, reports, and other non-peer-reviewed journal literature, and the Defense Technical Information Center (DTIC) database. We also conducted searches in Google Scholar to locate reports related to sleep in military populations published by such agencies
Table 1.1. A Crosswalk Between Research Questions and Study Methods Used
as DCoE, the North Atlantic Treaty Organization (NATO) Research and Technology Organization, and the Naval Center for Combat and Operational Stress Control. Then, we performed an iterative search using the reference lists from the publications retrieved from our initial search results to identify articles that we may have missed.
We also located the sleep-related publications of known experts in the field of military health and consulted with these experts to verify that we did not miss any relevant publications. Sources underwent successive rounds of screening, including a title and abstract review, followed by a full-text review, to exclude irrelevant or unsuitable articles. Articles selected for inclusion were then reviewed, and details relating to the focus of our study were abstracted. Appendix B provides more detail on the literature search methods for our review of the epidemiology of sleep in the military, as well as search terms used (Table B.1), studies on the prevalence of sleep problems in the post-deployment period (Table B.2), studies on the purported risk factors for sleep disturbances and cross-sectional studies of correlates of sleep problems (Table B.3), and longitudinal studies of sleep disturbances and mental and physical health and operational readiness (Table B.4). Appendix C provides additional background on evidence-based practices to treat sleep disorders in servicemember populations and includes a list of studies of cognitive-behavioral therapy for insomnia (CBT-I; Table C.1), imagery rehearsal therapy (IRT; Table C.2), complementary and alternative medicine (CAM; Table C.3), and CBT combinations (Table C.4), all of which focused exclusively on servicemember and veteran samples.