Study: Limited Evidence that Cannabis ‘Hangovers’ Stymie Performance

A new study by researchers at Australia’s University of Sydney suggests that there is little evidence to support the notion that cannabis “hangovers” can stymie performance. The researchers evaluated 20 published studies investigating the effects of THC more than eight hours after consumption and found most didn’t detect “next day” effects of cannabis use and the studies that did were limited. 

“Some lower quality studies have reported ‘next day’ effects of THC on cognitive function and safety-sensitive tasks. However, most studies, including some of higher quality, have found no such effect. Overall, it appears that there is limited scientific evidence to support the assertion that cannabis use impairs ‘next day’ performance. Further studies involving improved methodologies are required to better address this issue.” — “The ‘Next Day’ Effects of Cannabis Use: A Systematic Review,” Cannabis and Cannabinoid Research, Dec. 6, 2022 

The researchers found that 61% of the reviewed studies found no “next day” effects caused by cannabis use, 35% found “unclear or ambiguous next day effects,” with just 4% finding negative “next day effects”; however, the researchers describe those studies as “low quality” and note that they were all published more than 18 years ago.  

In a press release, Dr. Danielle McCartney, a research fellow with the University of Sydney’s Lambert Initiative for Cannabinoid Therapeutics, noted that individuals are told “not to drive or perform other safety-sensitive tasks for 24 hours after cannabis use,” but the study “found little evidence to support this recommendation.”  

“Policy makers should bear in mind that the implementation of very conservative workplace regulations can have serious consequences, such as termination of employment with a positive drug test,” the study authors said. “They can also impact the quality of life of individuals who are required to abstain from medicinal cannabis used to treat conditions such as insomnia or chronic pain for fear of a positive workplace or roadside drug test.”