Jennifer Ellis is an Assistant Professor and lisenced clinical psychologist in the Department and Behavioral Sciences at the Johns Hopkins University School of Medicine. Her research centers on understanding and addressing polysubstance use and co-occurring disorders, with a particular focus on sleep, chronic pain, and affective symptoms. She is also interested in emerging drug trends (e.g., xylazine, opioid-stimulant polysubstance use) and their implications for treatment. Dr. Ellis employs latent variable modeling to identify subgroups with distinct clinical needs and to examine how fluctuations in symptoms like craving and mood affect treatment outcomes. She has authored over 70 peer-reviewed publications and serves as site principal investigator and co-investigator on several NIH and industry-funded trials. Clinically, she provides care to individuals with substance use disorders in intensive outpatient settings. Dr. Ellis completed her Ph.D. at Wayne State University, her clinical internship at Yale University School of Medicine, and a NIDA T32 postdoctoral fellowship at Johns Hopkins.