Eating edibles can be a fun way to relax after a long week or a tool to promote a restful sleep, but some can wake up feeling groggy the next day. And those who have been to a secret sesh or cannabis event with all night smoking might wake up feeling the same. Some may wonder whether that feeling is a cannabis hangover, but that term may not fit.

What is a hangover, really?

A hangover is a set of symptoms related to drinking too much, according to the National Institute on Alcohol Abuse and Alcoholism (NIAAA). The NIAAA lists several factors that contribute to an alcohol-induced hangover, like dehydration, disrupted sleep, gastrointestinal irritation, increased inflammation, acetaldehyde exposure, and mini withdrawal.

Sulfites used to preserve wine and congeners, a byproduct of alcohol fermentation, also contribute to hangover symptoms. Headache, nausea, and other post-drinking symptoms peak when blood alcohol content returns to zero and can last as long as 24 hours.

Alcohol hangovers result from substances and side effects specific to alcohol. Though symptoms differ, excessive cannabis consumption can leave people feeling lethargic or foggy the next-day. But is it a hangover?

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Researching the cannabis hangover

A 1984 research team set out to discover if cannabis could produce a “hangover” the morning after consumption in a placebo-controlled study. The team monitored 13 male cannabis smokers directly after consuming either 2.9 percent or 0.0 percent THC and nine hours later. Those who consumed cannabis showed acute effects directly following consumption and different effects over nine hours later.

Approximately nine hours after smoking, those who consumed THC showed significant changes in the ability to do minor tasks like card sorting and memory recall. The study concluded that cannabis could have an effect the morning after, but that suggested more research was required to understand the extent of a cannabis hangover.

Cannabis and Cannabinoid Research Volume Eight included a systematic review of studies investigating what researchers referred to as the “next-day effects” of cannabis consumption. The review dissected 345 performance tests from 20 relevant studies published as recently as March 28, 2022.

The team collected studies from two databases and assessed the Risk of Bias (RoB) using five points of bias. How randomized the process was, how researchers strayed from the intended outcome, and whether they selectively reported, measured, or reported outcome data all impacted the RoB. Each study reviewed showed either “some” or “high” RoB.

Most studies administered a single dose of THC before monitoring subjects eight to 24 hours after consumption. Seven studies used oral consumption methods, and 13 opted for smoking. Nine of the 16 studies used placebo-controlled, randomized, double-blind designs.

Hours after consuming, subjects were assigned safety-focused tasks like driving simulators and a wide range of neuropsychological tests covering things like processing speeds and problem-solving.

Of the 20 published studies, 16 showed THC had no “next-day effects”. When looking at the 345 tests individually, 209 failed to demonstrate “acute” THC-induced impairment less than eight hours after consumption.

Five published studies showed 12 subjects who experienced “next-day” effects of THC. These five studies were published 18 to 30 years ago, and none were randomized, placebo-controlled, or double-blind. Insufficient information led to 121 tests showing “next-day” effects were “unclear,” and three tests indicated subjects were still affected by THC the next-day.

Cannabis hangover or “next-day” effects

A GreenState deep dive on how long edibles last revealed that the effects of eating an edible can last up to 24 hours–supporting the idea that subjects were still high rather than experiencing symptoms reminiscent of a hangover.

This data applies to edibles but not smoking and inhalation methods. More research is required to understand how much and what consumption method contributes to feeling altered the day after consuming.

Some research, though very little, does suggest that cannabis consumers could wake up still feeling high or impaired, does it qualify as a hangover? Not really. The term hangover is specific to physiological symptoms that cannabis doesn’t cause, even the day after. Perhaps the research team above was on to something.

The term “next-day” effects may better represent the anomaly of feeling lethargic the day after consuming cannabis. When it comes to safety, it’s best not to get behind a forklift less than 24 hours after consuming cannabis of any form.