The strongest link between marijuana use and sleep problems was found in adults who started using the drug before age 15. They were about twice as likely to have severe problems falling asleep, the study authors said.
The debate about marijuana has been heating up as it has been legalized in two states and approved for medical use in others.
Study lead author Jilesh Chheda, a research assistant at the University of Pennsylvania's division of mood and anxiety disorders, said in the Sleep Societies' news release: "Marijuana use is common, with about half of adults having reported using it at some point in their life. As it becomes legal in many states, it will be important to understand the impact of marijuana use on public health, as its impact on sleep in the 'real world' is not well known."
The federal government lists marijuana as a "schedule 1 substance" that has no medicinal uses and is a high risk for abuse, according to the U.S. National Institute on Drug Abuse.
Paul Armentano, deputy director of NORML, a group that lobbies for the legalization of marijuana, said the "association reported in this paper of a history of cannabis [marijuana] use and severe difficulty falling asleep is relatively minor and it is questionable whether it holds any real world relevance.
"The ongoing criminalization of cannabis and those who consume the plant is a disproportionate response to what is, at worst, a public health concern -- not a criminal justice matter," he added.
Health concerns about marijuana, particularly its potential use or abuse by young people, are best handled by regulation, public education and age restrictions, "not by criminalization and stigmatization," Armentano said.