Smoke, Sip, Sleep, Repeat: Investigating Daily-Level Bidirectional Relationships Between Separate and Simultaneous Alcohol-Cannabis Use and Sleep

Abstract

Objective: Many young adults use alcohol and cannabis to regulate sleep. Given the high prevalence of simultaneous alcohol–cannabis use in this population, there is a need to clarify the association between simultaneous use and sleep. This study examined daily relationships between simultaneous use (vs. cannabis-only, alcohol-only, and no use) and key sleep indices (i.e., subjective sleep quality, sleep duration, and bedtime), exploring the moderating role of substance use problem severity. Method: Young adults ( N = 150; 64% female; M age = 22.09) completed daily morning surveys in a smartphone app assessing prior-day alcohol and cannabis use, as well as sleep indices for the previous night. Participants also completed measures of alcohol and cannabis problem severity at baseline. Results: Compared with simultaneous use days, participants reported worse sleep quality and shorter sleep duration on alcohol-only days, earlier bedtime on cannabis-only days, and poorer sleep quality and earlier bedtime on no use days. Further, individuals with greater alcohol problem severity reported shorter sleep durations on alcohol-only and cannabis-only days than simultaneous use days, as well as later bedtimes on alcohol-only versus simultaneous use days. By contrast, those with lower alcohol problem severity reported earlier bedtimes on no use days and alcohol-only days compared with simultaneous use days. Cannabis problem severity did not moderate any day-level associations, and sleep outcomes were not significantly associated with the likelihood of engaging in next-day simultaneous use. Conclusions: Findings illuminate the daily-level relationships between simultaneous alcohol–cannabis use and sleep. Future research should explore tailoring sleep interventions based on simultaneous use behavior.