Study: Medical Marijuana Linked to Sustained Improvements in Sleep Quality Over One Year

A yearlong study following adults newly enrolled in Pennsylvania’s medical marijuana program found sustained improvements in self-reported sleep quality, with benefits appearing early and remaining stable over time. The research was conducted by investigators from Philadelphia College of Osteopathic Medicine and published in the Journal of Cannabis Research. Poor sleep is one of the most frequently cited reasons patients turn to medical marijuana, yet data on longer-term outcomes have been limited. To address this gap, researchers tracked 137 adults who were newly referred for medical marijuana treatment and assessed changes in sleep quality over a 12-month period.

Participants completed the Pittsburgh Sleep Quality Index at the start of the study and again at 3, 6, 9, and 12 months. The index produces a global sleep score, with higher scores indicating worse sleep, along with several subscales measuring different aspects of sleep quality. Researchers used statistical models to examine how these scores changed over time and whether outcomes differed based on preferred method of use or the medical condition that prompted the referral.

The analysis found that global sleep scores were significantly worse at baseline than at every follow-up point, indicating meaningful improvements in sleep quality after starting medical marijuana. Notably, there were no significant differences among the follow-up assessments themselves, suggesting that the improvement occurred relatively early and was maintained throughout the year. Improvements were seen across all measured aspects of sleep.

The study also found no significant relationship between sleep outcomes and whether patients preferred oral products or other forms of administration. Similarly, sleep improvements did not differ based on whether patients were referred for chronic pain, anxiety, or post-traumatic stress disorder.

Researchers caution that the findings rely on self-reported sleep measures and note that controlled studies using objective sleep data are needed to better understand how medical marijuana affects sleep over time.