With more students than ever before turning to weed to alleviate the stress of academic life, it’s no wonder they’re also wondering how the herb affects their studies. But can cannabis help or hinder your studying? Does it matter when you smoke? Could weed actually be a study aid? Or is there truth to the age-old stigma that if you’re blazing throughout your education, you’re destined to flunk out? Let’s see where cannabis fits into the world of studying; what it’s good for, and what it’s not.

As cannabis can affect us all differently, this is actually a tricky question to answer. For some people, weed can help with focus. For others, it only benefits brainstorming and creative thinking, while sabotaging deeper focus. According to this 2011 review cannabis does impair certain executive functions in the brain, generally lowering reaction times, uptake of information and also affecting memory. Science would seem to suggest that, for most, studying while high probably won’t be very beneficial.

But, aside from the immediate, are there longer lasting effects of smoking after studying? Will that evening joint affect your memory formation in the long run? We spoke with Emma Chasen, plant science expert, industry consultant, and cannabis educator with the Sativa Science Club, to learn what’s going on in the brain with cannabis and memory.

As you’re probably aware, there are many different types of memory, from short-term and working memory, to verbal, spatial, and long-term memory. Chasen explains, however, that there’s only one neurotransmitter that regulates all types of memory: Acetylcholine. “Acetylcholine is the main neurotransmitter that regulates memory and it can regulate short term, long term, as well as diseases like dementia and Alzheimer’s and other kinds of memory loss and amnesia experiences,” explains Chasen.

“Memory problems arise when you’re not at optimal levels of acetylcholine,” Chasen says. “This can get kind of tricky, because if you have too much acetylcholine, it’s not a great thing, and if you have too little, it’s not great either.” To understand the mechanisms at work, Chasen also explains that there’s an enzyme that breaks down acetylcholine, known as acetylcholinesterase. Its job is to help you maintain optimal levels of acetylcholine in the brain.

Here’s where cannabis comes in: THC is an acetylcholinesterase inhibitor, meaning it stops, or “inhibits” the enzyme from breaking down more acetylcholine. “That’s good if you need more acetylcholine, not so good if you don’t need more,” says Chasen. “That’s where THC can negatively impact short-term memory specifically.”

Basically, THC is interfering with our brain processes that regulate memory by inhibiting acetylcholinesterase’s functions. Therefore, memory formation and recall is slightly impaired. But here’s the kicker: this impairment only lasts as long as you are “high.” Once the effects of THC wear off, so does the minor cannabis memory loss.

“There’s no research to support that prolonged use of THC will actually mess up your spatial memory [or other types of memory] in the long term. But in the short term, it can definitely have some negative side effects,” says Chasen. So there you have it. THC has no lasting effect on your memory, that we know of at least. But it can impair you while you’re high.

Our advice? It’s probably best not to study while high, because THC could be interfering with your retention of the material. Don’t smoke until after you’re done studying for the night and it shouldn’t affect your retention or understanding of the information.

There’s more to cannabis than just THC; other components have counteracting effects of their own. If THC and CBD were a good cop bad cop crime-fighting duo, CBD would definitely be the good cop. CBD, a non-intoxicating cannabinoid, is known to counteract many of the effects of THC, and that includes cannabis memory loss.

“CBD, when in conjunction with THC, can actually help to optimize your levels of acetylcholine,” says Chasen. “So, if you are consuming something that has a significant concentration of THC but also has a significant concentration of CBD, then you’re less likely to experience memory deficits or memory issues. Again, this is specifically related to short-term memory.”

Therefore, in order to avoid any cannabis memory loss after studying, look for strains with high levels of CBD, especially those with a ratio of 1:1 or 2:1 CBD to THC. Some popular high CBD strains include Sour Tsunami and Cannatonic.

THC and CBD aren’t the only compounds in cannabis that affect memory. Some terpenes also play a part in reversing the effects of THC on short-term memory. “Pinene also has acetylcholinesterase inhibitor action that can also help to reverse the negative side effects of short-term memory loss in over-consumption of THC,” says Chasen.

The terpene pinene was named for its pine aroma, and has a range of medicinal properties. It’s one of the “major” terpenes in cannabis and also has anti-anxiety, anti-inflammatory, and bronchodilator effects. Some great strains high in pinene to keep your cannabis memory loss at a minimum include Jack Herer and Strawberry Cough.

While cannabis has some wonderful benefits for post-studying, getting high before an exam is probably not the best thing to do. You need your brain firing on all cylinders, and THC’s temporary impairment of short-term memory means your performance during an examination could easily suffer.

Save the spliffs for after your exam to wind down, and study and take your tests with a clear head and you should be good to go. That is assuming you already know how to study successfully!