Jeffrey WardellNicolle J Fox2023-08-042023-08-042023-08-04https://hdl.handle.net/10315/41399Rates of alcohol and cannabis use are highest among Canada’s young people. Unplanned substance use among young adults is associated with heavier use and greater harms than planned use. Although previous research has found associations between mood and alcohol use, there has been less research on the role of mood in unplanned use. This study examined daily associations between mood and unplanned alcohol and cannabis use and explored the role of impulsivity in this relationship. Data came from a 21-day ecological momentary assessment (EMA) study, in which young adults, aged 19-25, completed daily surveys assessing intentions for use, and previous day substance use, as well as randomly timed surveys capturing momentary mood states. Impulsive personality traits were assessed at baseline through the UPPS-P Impulsive Behaviour Scale. Multilevel models showed significant daily-level relationships of increased positive mood and decreased negative mood with greater likelihood of unplanned vs. planned drinking. Several impulsive traits weakened the association between mood and unplanned alcohol use, such that high impulsivity appeared to reduce the impact that daily increases in positive mood and decreases in negative mood had on likelihood of unplanned alcohol use. An exception to that was lack of premeditation and perseverance, which strengthened the relationship between daily changes in positive mood and unplanned drinking. Boredom had a nuanced relationship with unplanned use, and impulsivity also appeared to weaken the association between boredom and unplanned drinking. Increases in boredom were associated with a decreased likelihood of unplanned cannabis use at the day level; however, impulsivity did not moderate associations between mood and unplanned cannabis use. These findings can help inform harm reduction interventions targeting unplanned substance use in a young adult population, given the prevalence and concurrent risks associated with unplanned alcohol and cannabis use.Author owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.PsychologyElectronic Thesis or Dissertation2023-08-04alcohol usecannabis useunplanned substance usemoodimpulsivity