Nicotine and Cannabis Co-Use and Sleep-Related Outcomes in Adults: A Narrative Review and Implications

Sleep is a critical determinant of physical and mental health, and substance use may affect sleep. Despite rising nicotine-cannabis co-use among adults, its impact on sleep remains poorly understood. This narrative review synthesizes recent evidence on nicotine-cannabis co-use and sleep-related outcomes in adults, highlighting patterns, methodological limitations, and future research directions.

Although substantial literature has examined nicotine or cannabis use and sleep independently, few studies have evaluated their combined effects. Only six studies published between 2015-2025 examined nicotine-cannabis co-use and sleep outcomes in adults. Co-use definitions varied (e.g., concurrent or dual use) and included multiple forms of nicotine and cannabis use (e.g., vaping or smoking). Sleep outcomes were primarily assessed via subjective measures (self-reported scales), with only one study using an objective measure (actigraphy-derived rest-activity rhythms). Findings were mixed: three studies linked co-use to poorer sleep, including short or long sleep duration, sleep disturbances, and disrupted rest-activity rhythms, and three studies reported null associations, potentially reflecting differences in populations, sample sizes, co-use definitions, or heterogeneity in sleep assessments.

Nicotine-cannabis co-use is prevalent and may confer greater sleep-related risks than single-substance use, with nicotine may drive most effects. However, evidence from the past 10 years is limited by a small number of studies with heterogeneous co-use definitions, small or non-representative samples, reliance on self-report, and cross-sectional study designs. Future research should standardize co-use definitions, incorporate validated objective sleep measures (e.g., polysomnography), assess timing, frequency, dose and use longitudinal designs to clarify causal relationships.