The intoxicating effects of alcohol and of marijuana have been widely studied, but their combined effect—getting “cross-faded”—is woefully underexplored, at least scientifically (right?)

Marijuana contains THC (tetrahydrocannabinol), which acts on the brain’s cannabinoid receptors. Alcohol depresses the central nervous system. Trying to compare the two isn’t even like comparing apples and oranges, says Gary Wenk, a professor of psychology and neuroscience at Ohio State University. “It’s apples and vegetables. They’re very different drugs.” An extremely simplified explanation would be to say that THC largely has cognitive effects, like paranoia and a distorted sense of time, while alcohol mainly affects motor skills, making it hard to walk in a straight line and causing slurred speech. The next time someone tells you their “fine” when they smoke as opposed to drinking, they might have a point, albeit skewed.

So does combining weed and alcohol just add their respective effects together? Not quite, says Scott Lukas, who teaches at Harvard Medical School and has researched the interaction of various drugs. In a study published in 2001, Lukas found that after individuals smoked marijuana and a drank large dose of alcohol, the equivalent to a couple of shots, the THC levels in their blood plasma nearly doubled compared with people who smoked pot and consumed a placebo drink. The buzzed people in the study also detected the effects of marijuana sooner than those who only got stoned, and rated their high as subjectively “better.” This suggests that getting boozed up causes more THC to reach the brain, via the bloodstream, within the first few minutes of ingestion. One explanation for this finding is that alcohol may cause changes in blood vessels that boost the absorption of inhaled THC. Cross-fading is definitely a riskier proposition, as you’d imagine.

More recent studies show the combination creates a more pronounced lethargic, demotivated effect in rats. Go figure. Nap anyone?

What Happens To Your Body When You Get Drunk And Stoned At The Same Time? | Popular Science.