By Nathan
Tobacco and cannabis are among the most commonly used psychoactive substances worldwide, and their co-use has risen sharply over the past decade as cannabis legalization expands across North America. Sleep is a critical health domain that both substances are known to affect individually, yet their combined impact on sleep has received surprisingly little scientific attention. A new narrative review from researchers at Yale School of Medicine takes stock of the limited evidence base, synthesizing six studies published between 2015 and 2025 that examined nicotine-cannabis co-use and sleep-related outcomes in adults. The findings, published in Current Addiction Reports, reveal a mixed picture. Three studies linked co-use to worse sleep outcomes, including short and long sleep duration, sleep disturbances, and disrupted rest-activity rhythms. Three others found no significant associations. The authors identify serious methodological limitations across the board, including heterogeneous definitions of co-use, small and non-representative samples, reliance on self-reported sleep measures, and near-total absence of objective sleep assessment.
Key points
The review, led by Wei Li and colleagues at the Yale Tobacco Center of Regulatory Science, identifies six eligible studies from a systematic search of four databases (PubMed, PsycINFO, Web of Science, and CINAHL). Only studies that measured co-use of nicotine and cannabis in adults, examined a sleep-related outcome, and were published in English were included. Four studies were cross-sectional, one was a longitudinal analysis, and one used ecological momentary assessment (EMA) with actigraphy.
Among the three studies that found positive associations, the most consistent finding was that co-users reported shorter or longer sleep duration compared with single-substance users or non-users. One study using data from the National Health and Nutrition Examination Survey (NHANES) found that adults who used both tobacco and cannabis were more likely to report short sleep (less than 7 hours) and long sleep (more than 9 hours), suggesting a U-shaped disturbance of sleep regulation. Another study found that co-users reported more insomnia symptoms and daytime sleepiness. The only study in the review to include an objective measure used wrist actigraphy and EMA over two weeks; it found that co-users had more disrupted rest-activity rhythms, including lower relative amplitude and greater fragmentation of activity patterns, compared with cannabis-only users and non-users.
The three null studies, by contrast, found no statistically significant differences between co-users and single-substance users on measures such as sleep quality, sleep efficiency, or insomnia severity. One study of young adults found no effect of co-use on self-reported sleep quality after adjusting for frequency and quantity of each substance, raising the possibility that confounding by heavier use patterns may drive the apparent associations seen in simpler analyses.
The review also grapples with a central interpretive question: is co-use worse for sleep than use of either substance alone? The authors note that nicotine is a well-established sleep disruptor, with stimulating effects that can increase sleep latency, reduce total sleep time, and cause nocturnal awakenings. Cannabis may have more complex and dose-dependent effects, with some users reporting improved sleep onset but also tolerance and withdrawal-related sleep disruption. The review suggests that nicotine may be the primary driver of sleep disturbances among co-users, but that larger, better-designed studies are needed to disentangle the independent and interactive effects of each substance.
A major theme of the review is definitional inconsistency. Some studies defined co-use as “concurrent” use (both substances used within a given period, such as the past 30 days), while others used “dual use” (regular use of both) or “co-administration” (using both substances at the same time, such as blunts or spliffs). These definitions have very different implications for potential pharmacokinetic interactions and for understanding the behavioral context of use. The review calls for standardized definitions to improve comparability across studies.
Implications
The mixed findings of this review do not support a simple conclusion that nicotine-cannabis co-use is uniformly harmful or benign for sleep. Instead, they highlight a research area in its early stages, where methodological heterogeneity and small sample sizes limit the ability to detect consistent effects. However, several actionable implications emerge.
For clinicians, the review underscores the importance of assessing both substances in patients presenting with sleep complaints, particularly given that each substance may contribute to sleep disruption through distinct mechanisms. Co-use should not be assumed to be equivalent to cannabis use alone, and nicotine cessation or reduction may be a particularly important target for improving sleep in this population.
For researchers, the authors offer a clear agenda. First, standardized definitions of co-use are essential. Without them, studies cannot be meaningfully compared or meta-analyzed. Second, objective sleep measures such as polysomnography (PSG) and actigraphy should be incorporated as a standard rather than an exception; only one of the six studies included any objective measurement. Self-reported sleep is known to correlate only modestly with physiological sleep, and both nicotine and cannabis can alter perception of sleep quality in ways that may distort subjective reports. Third, longitudinal and experimental designs are urgently needed. Cross-sectional studies cannot establish whether co-use precedes poor sleep, whether poor sleep increases substance use, or whether a third factor (such as anxiety, depression, or socioeconomic disadvantage) drives both.
From a public health perspective, the rising prevalence of cannabis use and nicotine-cannabis co-use, particularly through vaping and edible products, makes this an increasingly relevant question. Policy changes around cannabis legalization have not been accompanied by sufficient research into the health consequences of combined use. Sleep is a modifiable risk factor for cardiovascular disease, metabolic disorders, and mental health problems, and understanding how co-use affects it is a matter of practical clinical urgency.
Source
Li W, Ferry F, Davis DR, Krishnan-Sarin S. Nicotine and cannabis co-use and sleep-related outcomes in adults: a narrative review. Current Addiction Reports. 2026. DOI: 10.1007/s40429-026-00738-y. PMID: 42466008. PMCID: PMC13374733. https://pubmed.ncbi.nlm.nih.gov/42466008/