Grant: TG: The Can. Cannabis/Brain Health Cons.- Contr.Trials Cannabis for Med purp.

Sleep problems affect nearly half of all Canadian adults and are a major contributor to poor mental and physical health. While approved sleep medications exist, many Canadians are now turning to legalized cannabis constituents (CBD, THC) to manage sleep challenges. Despite widespread use and potential short-term improvements in sleep, there is limited scientific evidence to guide safe and effective use of cannabis for sleep or how it may impact long-term mental and physical health. This gap has created uncertainty for individuals, healthcare providers, and policymakers. This project addresses this gap through two complementary approaches. First, we will follow a large, nationally representative cohort (N=450) to observe how patterns of cannabis use relate to sleep and brain health over time using at-home sleep monitoring. Second, we will conduct a randomized, placebo-controlled trial (RCT) to determine whether oral THC or CBD can improve sleep and related brain health outcomes in people with post-traumatic stress disorder (PTSD; N=150). PTSD affects nearly 8% of Canadians and is strongly associated with chronic sleep disturbances. Many individuals with PTSD report using cannabis to manage sleep. By focusing on this population, the study will directly test whether cannabis constituents improve sleep as a central driver of adjacent mental health and physical health indicators in a subgroup of the Canadian population where the magnitude of potential benefits and risks are particularly significant. Cannabis use is increasing across Canada, and at the same time new technologies now allow for at-home monitoring of sleep and brain activity, enabling large-scale, real-world data collection that was not previously feasible, increasing. By integrating population-level data with a RCT, this study will provide the most comprehensive evidence to date with regards to how cannabis affects sleep and brain health across diverse general and at-risk populations.