Summary: New research finds that individuals who begin regular cannabis use before age 18 are more likely to experience insomnia and short sleep duration in young adulthood.
Source: University of Colorado
Frequent cannabis use during adolescence is linked to higher rates of insomnia and shorter sleep in young adults, according to a new study of more than 1,800 twins from the Colorado Twin Registry.
A study published in the journal Sleep examined how the onset of regular cannabis use relates to insomnia and short sleep in young adults. The research arrives as cannabis products—ranging from high-potency vape cartridges to THC-infused edibles—are increasingly promoted as sleep aids in jurisdictions where they are legal. While occasional use may help some people fall asleep, the new findings add to evidence that habitual use, especially beginning in adolescence, can have lasting negative effects on sleep.
“People often assume cannabis helps with sleep, but continued or excessive use is associated with sleep deficits,” said lead author Evan Winiger, a graduate student in the Institute for Behavioral Genetics. “Our analysis is the first to show that early regular use is associated with increased rates of insomnia later on.”
Winiger and colleagues analyzed survey data from 1,882 twins (56% female, mean age 22.99) enrolled in the Colorado Twin Registry, which has tracked twins for research since 1968. Participants reported their sleep habits, cannabis use history, and mental health. Researchers controlled for factors known to affect sleep, including current depression symptoms, prior diagnosis of anxiety or depression, and shift work.
The study found that about one-third of participants who began using cannabis regularly before age 18 reported insomnia in young adulthood, compared with under 20% of those who did not use cannabis regularly as teenagers. The pattern was similar for chronic “short sleep” (regularly sleeping fewer than six hours per night): roughly 10% of early regular users were short sleepers as young adults, versus about 5% of non-regular teen users. Participants who started regular cannabis use after age 18 also showed modestly higher rates of insomnia.
Possible explanations: brain development, habits, and genes
The mechanisms behind the association are not fully resolved, but several plausible explanations exist. The body’s endocannabinoid system produces compounds similar to THC and CBD that bind to brain cannabinoid receptors and help regulate cognition, emotion and circadian rhythms. Heavy exposure to cannabis during adolescence—when the brain is still maturing—could desensitize or alter these receptors and affect sleep regulation later in life.
Adolescent cannabis use might also produce structural changes in developing brain regions involved in sleep regulation; prior imaging studies have observed changes in the prefrontal cortex among young users. Alternatively, repeated cannabis use in the teen years could establish sleep patterns or behaviors that persist into adulthood.
Genetic factors appear to play a role as well. By comparing 472 identical twin pairs (who share 100% of their genes) and 304 fraternal pairs (who share about 50%), the researchers estimated genetic and environmental contributions to both early cannabis use and insomnia. They report substantial heritability for onset of regular cannabis use (a2 = 76%), insomnia (a2 = 44%), and insomnia with short weekday sleep (a2 = 37%). Significant genetic correlations were found between early cannabis use and insomnia (rA = 0.20) and between early use and insomnia with short sleep (rA = 0.25). The authors did not detect significant environmental correlations between these traits.
These genetic findings mean some of the same inherited factors that increase the likelihood of early regular cannabis use may also increase the risk of later insomnia. As the authors note, causality remains unresolved: sleep problems could predispose some people to use cannabis, cannabis use could contribute to sleep problems, and shared genetics could underlie both outcomes.
Co-author Ken Wright, director of the Sleep and Chronobiology Lab, emphasized that the results do not prove that all cannabis products harm sleep for every person. “The evidence in adults is mixed, and some studies have found short-term sleep benefits with infrequent use,” he said. However, he cautioned against recommending cannabis to adolescents as a sleep aid: “When dealing with a developing brain, caution is warranted.”
Source:
University of Colorado
Media Contacts:
Lisa Marshall – University of Colorado
Image Source:
The image is in the public domain.
Original Research: Closed access. “Onset of regular cannabis use and young adult insomnia: an analysis of shared genetic liability.” Evan A. Winiger, Spencer B. Huggett, Alexander S. Hatoum, Naomi P. Friedman, Christopher L. Drake, Kenneth P. Wright, Jr., John K. Hewitt. Sleep. DOI: 10.1093/sleep/zsz293.
Abstract (summary)
The study used a population-based twin cohort of 1,882 participants to estimate genetic and environmental influences on the relationship between the onset of regular cannabis use and insomnia-related outcomes. After adjusting for sex, current depression symptoms, and prior diagnoses of anxiety or depression, early onset of regular cannabis use (age 17 or younger) was associated with higher likelihood of insomnia (β = 0.07, p = 0.024) and insomnia with short weekday sleep (β = 0.08, p = 0.003) in young adulthood. The analysis found significant heritability for early regular cannabis use and for insomnia outcomes, as well as significant genetic correlations linking early cannabis onset with both insomnia outcomes, suggesting pleiotropic genetic influences.