Why users mix substances: Tracking daily motivation patterns

This study examined how young adults' reasons for using alcohol and cannabis vary from day to day and how different combinations of motives relate to substance use patterns. Researchers tracked 328 college students over 54 days, collecting 5,907 daily reports where participants recorded why they used (or didn't use) substances and what consequences they experienced. The analysis identified six distinct daily patterns: fun-only days, social-and-fun days, availability-driven days, exploration-and-fun days, coping days, and days with multiple strong motivations. Understanding these day-level patterns reveals that substance use motives are not static—they shift based on daily circumstances and emotional states.

The most important finding was that days involving multiple motives showed the highest substance use and negative consequences, particularly when both alcohol and cannabis were used together (co-use). Days driven by coping motives and those with generally high motivation across all reasons showed the most severe outcomes, including greater quantities used and more substance-related harms. In contrast, fun-only or simple social motivations were associated with more moderate use patterns. The study reveals that young adults aren't using substances for a single reason; most use days involve overlapping motivations that amplify both use intensity and potential harms.

These findings have practical implications for prevention and intervention strategies. Since motives vary predictably across days, targeted just-in-time interventions—delivered when individuals are most vulnerable—could help interrupt problematic use patterns before they escalate. Understanding that coping-motivated use and complex motive combinations drive the highest harms suggests that interventions should address underlying emotional regulation and stress management, not just discourage substance use itself.