Cannabis use is linked to an increased likelihood of sleeping problems, according to a new study from researchers at the University of Pennsylvania in Philadelphia and presented at the SLEEP 2014 meeting.
Marijuana use is common, with reports suggesting that half of adults in the US have used the drug at some point in their life. Now that marijuana is being legalized in some states, it is becoming increasingly important to understand the impact this drug might have on public health.
In April this year, Medical News Today reported on a study published in the Journal of Neuroscience where researchers used magnetic resonance imaging (MRI) to scan the brains of 40 regular marijuana smokers aged 18-25.
Comparing the scans with brain scans of individuals with little or no history of marijuana use, the researchers found that the area of the brain responsible for reward processing - the nucleus accumbens - was larger and had an altered shape and structure in the marijuana users.
The amygdala - a region of the brain involved in emotion - also displayed abnormalities in marijuana smokers, with the abnormalities being greater the more marijuana was smoked by the participants.
And a 2013 study, by researchers at the Feinburg School of Medicine at Northwestern University in Illinois, found that heavy use of marijuana produces changes in brain function that result in schizophrenia-like symptoms.
People who started using marijuana early were more likely to have sleep problems as an adult.
In the new study, the researchers analyzed data from the 2007-2008 National Health and Nutrition Examination Survey (NHANES). They looked at 1,811 adults aged 20-59 who had reported using cannabis. NHANES collected information on sleeping patterns, at what age the participants first used the drug and the number of times they had used the drug in the past month.
The full results of the new study will be presented on June 4th in Minneapolis, MN, at SLEEP 2014, the 28th annual meeting of the Associated Professional Sleep Societies, LLC.
In advance of that presentation, though, the researchers have announced that they found current and past marijuana users are significantly more likely to experience sleep problems than non-users.
"The most surprising finding," says lead author Jilesh Chheda, research assistant at the University of Pennsylvania in Philadelphia, "was that there was a strong relationship with age of first use, no matter how often people were currently using marijuana. People who started using early were more likely to have sleep problems as an adult."
Study type cannot determine causality, only demonstrate a link
The research shows a link between initiation of marijuana use in adolescence and a higher risk for subsequent insomnia symptoms. However, the type of study used in this research does not allow the authors to determine causality, so they cannot say that marijuana use definitely causes insomnia.
For instance, people who begin using marijuana earlier may experience insomnia for other reasons, such as stress. Also, insomnia could be a reason why some people begin or continue to use marijuana.
Marijuana use has been increasing among young people since 2007, according to the National Institute on Drug Abuse. It is possible that the public debate over the legal status of the drug may have contributed to this escalating use. Colorado and Washington have legalized the drug for recreational use among adults, and 21 states now allow the use of marijuana as a medical treatment.