Veterans’ rates of sleep disorders have been increasing over the past 20 years, and millions report shorter than recommended sleep durations for optimal sleep health. Contemporaneously, ongoing cannabis legislation in the U.S. has increased access to, and availability of, cannabis products distinct by mode, formulation, and cannabinoid composition. Moreover, as cannabis’ perceptions of harm are declining, widespread beliefs about its therapeutic benefits are increasing and cannabis use disorder (CUD) remains prevalent. For example, one of the most common reasons Veterans use cannabis is for sleep. However, cannabis’s effect on sleep is unclear, likely due to a reliance on self-reports, cross-sectional data, and insufficient attention to cannabis product type. Laboratory studies also administer cannabis with limited cannabinoid profiles and lower potency compared to commercially available products used for sleep in the real-world. Equally important, cannabis/sleep research has not adequately prioritized Veterans as prior findings come almost exclusively from civilian populations. Smartphone apps and wearable technologies are valuable and unobtrusive tools to generate fine-grained data on substance use and health behaviors. These technology-based-tools (TBTs) have considerable promise to help understand how cannabis and sleep are related and identify potential prevention and intervention targets tailored to Veterans. As such, the primary research objective of this Career Development Award-2 (CDA-2) is to prospectively examine bi-directional relations between cannabis and sleep among non-CUD-treatment seeking Veterans in the natural environment. Participants will first complete a 30-day pilot study by wearing a Fitbit device and using an EMA app on their smartphone to measure cannabis use and sleep in the field followed by individual interviews to determine protocol feasibility, acceptability, and adherence (Phase I, Aim 1). After refining the study procedures based on results from the prior phase, Phase II research will evaluate bi-directional links between cannabis use and sleep physiology/behaviors during a 30-day observational field period (Aim 2.1), explore participants’ lived experiences using cannabis for sleep (Aim 2.2), and determine which specific cannabis modes, formulations, or cannabinoid compositions are most harmful (or helpful) to self-reported and technology- derived sleep behaviors (Aim 2.3). Dr. Berey has demonstrated considerable scholarly productivity with an established track record of using different TBTs in substance use research. This CDA-2 proposal aims to accelerate Dr. Berey’s training in cannabis and sleep using TBTs, and to launch his VA-based research program. A collaborative and coordinated mentor team will facilitate his successful transition to independence via training in: 1) EMA and wearable technologies (Drs. McGeary and Merrill), 2) cannabis use among Veterans (Dr. Metrik), 3) measurement and core components of ...