Millions of people use cannabis as a form of sleep aid, but despite the widespread view that it can help you get a good night’s rest, the evidence is starting to suggest otherwise – with scientists even linking it to sleep disruption, reports ScienceAlert.
In recent years, reviews have also suggested that the drug may, in fact, have an overall detrimental effect on sleep quality, despite what many users might think it’s doing for them.
A recent study, in JAMA Network Open, highlights this paradox, suggesting a possible disconnect between the sleep quality of cannabis users and their own perception of how well they’re sleeping.
In an analysis of 35 years of observational data from participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study, the researchers found that cannabis use was associated with multiple objective measures of poorer sleep.
Subjectively speaking, however, based on questionnaires in which participants rated their sleep quality, there was no sign that those using the drug felt their sleep was negatively affected.
“This study challenges the common belief that cannabis helps people sleep better,” said epidemiologist Thanh-Huyen T. Vu from Northwestern University in Illinois, United States.
“Our findings suggest cannabis may actually be associated with poorer sleep quality, even if people don’t perceive those changes.”
The CARDIA study began recruiting participants in 1985 from four sites across the US, ultimately involving more than 5 000 people. Participants completed several follow-up examinations as the study progressed, with the ninth follow-up assessment taking place in 2022 (year 35 of the study).
In the new analysis by Vu’s team, the researchers looked at data from 1 266 participants in the CARDIA cohort, including 1 128 people who self-reported sleep assessments at the end of the study period.
They also analysed objective sleep data from 891 participants who used a wrist-worn tracker to monitor their sleep for seven days, with 753 people contributing to both the subjective and objective analyses.
After adjusting for age, race, sex, education level, smoking and alcohol use, and other factors, the researchers found that greater lifetime cannabis use was associated with a lower sleep percentage (the amount of time asleep during sleep periods), higher sleep fragmentation, and waking up for longer periods during sleep.
Each additional year of cannabis use was linked with poorer sleep, equating to 10% higher odds of a low sleep percentage (spending less than 85% of the sleep period asleep), 4% higher odds of high sleep fragmentation, and 21% higher odds of prolonged waking up (spending at least 30 minutes awake in total during sleep periods).
Among recent cannabis users (participants who had consumed the drug within the last 30 days), cannabis use was linked with longer sleep duration (20 minutes extra per night), but also with lower sleep percentage, higher sleep fragmentation, and longer periods of waking up, compared witho people who had never used the drug.
Yet despite all these objective measurements indicating poorer sleep, neither lifetime nor recent cannabis use was associated with the participants reporting lower subjective sleep quality, the researchers note.
“This was one of the most interesting findings,” Vu said. “The wearable device detected more night-time disruption among participants with long-term cannabis exposure, but the participants themselves generally did not report worse sleep.”
While it’s not completely clear why this is happening, the researchers say the discrepancy could have important public health implications, especially given cannabis’ popularity and reputation for being a supposed sleep aid.
“Individuals may not perceive declines in sleep quality or may interpret longer sleep duration as improved sleep despite objectively poorer sleep,” they wrote in their paper. “Thus, cannabis-related sleep disturbances may go unrecognised.”
The researchers noted that previous studies examining cannabis’s effects on sleep quality have shown mixed results, but they observe that many were limited by small samples, short follow-up periods, or cross-sectional designs that didn’t examine how long-term cannabis use is associated with sleep quality, and few studies have incorporated objective sleep data.
Further, some studies examining the effects of medical cannabis may have only looked at sleep as a secondary outcome, or may have assessed it alongside other factors that may affect sleep.
“One possible explanation for the small improvement in subjective sleep quality observed in these medical cannabis studies is that most participants were from clinical populations with pain, cancer, or sleep disorders,” the researchers write.
“Cannabis may improve perceived sleep quality by reducing symptoms that interfere with sleep, even when objective sleep measures show little or no change.”
Given this was an observational study, the research can’t establish whether cannabis use directly caused the sleep disturbances people experienced.
The researchers also acknowledge a number of limitations, including that they didn’t track cannabis potency or timing relative to sleep, and while their study did incorporate objective sleep measurements, they were only able to access a week’s worth of sleep tracking data (over a study period lasting decades).
They suggest future long-term studies with objective sleep assessments will be able to better clarify how cannabis use influences sleep.
Study details
Recent and Cumulative Cannabis Use and Sleep in Middle-Aged Adults
Thanh-Huyen T. Vu, Kristen Knutson, Reto Auer et al.
Published in JAMA Network Open on 9 October 2026
Abstract
Importance
Cannabis is widely used and often promoted as a sleep aid, but evidence of its long-term implications for sleep is limited.
Objective
To examine the associations of cumulative cannabis exposure from young adulthood to middle age and recent cannabis use with objective and subjective sleep outcomes in middle age.
Design, Setting, and Participants
This cohort study analysed data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, including 35 years of follow-up through the year-35 examination (conducted in 2020 to 2022), and the CARDIA Year-35 Sleep Ancillary Study. Analyses were conducted from January 15 to July 15, 2026.
Exposures
Cumulative cannabis use (calculated in cannabis-years, with 1 cannabis-year equating to 365 days of use) and recent cannabis use (defined as past 30-day use vs former use and never use).
Main Outcomes and Measures
Objective sleep was assessed using data from 7-day wrist actigraphy, and subjective sleep was assessed with the Pittsburgh Sleep Quality Index (PSQI). Primary outcomes and measures were objective sleep duration (categorized as short [<6 hours], optimal [6-8 hours], or long [>8 hours]), sleep percentage (defined as percentage of time asleep; low percentage: <85%), sleep fragmentation (defined as the index of restlessness during sleep; high fragmentation: highest quartile), and wakefulness after sleep onset (WASO; prolonged WASO: ≥30 minutes) and subjective sleep quality (PSQI score and poor sleep quality: PSQI >5).
Results
A total of 1266 participants (891 with objective and 1128 with subjective sleep data) were analysed. Among the 891 participants with objective sleep data, the mean (SD) age at the year-35 examination was 60.7 (3.6) years; the cohort included 564 females (63.3%) and 365 Black (41.0%) and 526 White (59.0%) participants. After multivariable adjustment, each additional cannabis-year was associated with higher odds of low sleep percentage (odds ratio [OR], 1.10; 95% CI, 1.06-1.14), high sleep fragmentation (OR, 1.04; 95% CI, 1.01-1.08), and prolonged WASO (OR, 1.21; 95% CI, 1.10-1.34). Compared with participants with former use and never use status, those with recent use had higher odds of low sleep percentage, high fragmentation, prolonged WASO, and long (vs optimal) sleep duration (eg, vs never use, prolonged WASO: OR, 3.23 [95% CI, 1.44-7.27]; long sleep duration: OR, 4.60 [95% CI, 1.81-11.70]). Cannabis use was not associated with subjective sleep quality.
Conclusions and Relevance
In this cohort study, both cumulative use and recent cannabis use were associated with poorer objective sleep quality, although no association with self-reported sleep quality was found. These findings underscore the importance of assessing both subjective and objective sleep and suggest potential adverse association between long-term recreational cannabis exposure and midlife sleep health.
See more from MedicalBrief archives:
Research busts myth of cannabis being good for sleep
AASM position statement on medical cannabis and obstructive sleep apnoea
Cannabis-like drug effective in treating sleep apnoea