A new study suggests that marijuana use is associated with impaired sleep quality.

Results show that any history of cannabis use was associated with an increased likelihood of reporting difficulty falling asleep and struggling to maintain sleep. Participants also reported experiencing non-restorative sleep and feeling daytime sleepiness.

“Current and past marijuana users are more likely to experience sleep problems,” said lead author Jilesh Chheda, research assistant at the University of Pennsylvania in Philadelphia, working with Dr. Michael Grandner, the senior author on the study.

The study involved adults ranging in age from 20-59 years who responded to the 2007-2008 National Health and Nutrition Examination Survey (NHANES). A history of drug use was reported by 1,811 participants. Cannabis use was assessed as any history of use, age at first use and number of times used in the past month. Sleep-related problems were considered severe if they occurred at least 15 days per month.

“Marijuana use is common, with about half of adults having reported using it at some point in their life,” said Chheda.  “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.”

According to the National Institute on Drug Abuse, marijuana use among young people has been on the rise since 2007. This may be due to increased public debate over the drug’s legal status.