Why does weed get you high?

When you ingest THC, it comes into contact with the cannabinoid receptors scattered around your brain and body. It’s like the THC presses buttons that turn on certain characteristic effects: euphoria, hunger, relaxation.

So if we have cannabinoid receptors, does that mean we’ve evolved to be potheads?

Cannabinoid receptors actually exist to receive naturally occurring chemicals called endocannabinoids. Part of your mood is due to the presence of them in your brain. When you take THC, you’re boosting the effects of these natural endocannabinoids.

Why does pot make you laugh?

The parts of your brain that govern mood and emotion, such as the limbic system, contain particularly high numbers of cannabinoid receptors. THC bonks those receptors in your nervous system, causing something called fatuous euphoria. You feel tremendously happy — and when you’re happy, you’re prone to laugh your head off, even if someone’s not telling a fantastic joke.

Then how come THC makes some people anxious and even paranoid?

You activate more receptors with higher doses of THC. Someone who has taken a higher dose may begin to feel things they didn’t expect, such as a racing heartbeat, so they can get very worried. Lower doses tend not to have that effect.

What if I’m so high I think I might be dying? Is there a way to undo it?

Theoretically, yes. There are certain drugs that turn off cannabinoid receptors. One of the only ones to come to market, rimonabant, promoted in Europe in the mid-aughts as a diet drug, was subsequently pulled because it caused depression and suicidal thoughts. So none are available to treat acute cannabis toxicity. It’s widely thought that taking CBD can lessen the effects of THC, but those claims have not been subject to wide scientific scrutiny. So it’s basically at the level of, “Try it, see if it works for you.”

How can I steer clear of a bad trip?

Beginners should remember to take it “low and slow” — start with low doses and slowly increase the quantity until you feel the right effects. Then stop. If you take too much THC, you’ll start to get side effects that are the antithesis of what you want to feel, like the paranoia or the very fast or very slow heartbeat. At extremely high-dose levels, the body starts to recognize THC as a toxin and will activate mechanisms in the brain that cause you to vomit.

Why do edibles take longer to work than smoking or vaping?

If you eat cannabis, it has to go through your stomach and your liver and only gradually gets into your bloodstream and to your brain. That’s why edibles can creep up on you.

I’ve heard that marijuana makes some people more productive or more creative. Is that possible?

It depends on what you mean by “productive.” If you’re an accountant and you’re crunching lots of numbers in a spreadsheet, being high on THC probably isn’t beneficial. That’s because cannabis has been shown to impair short-term memory functions by impacting parts of the brain such as the hippocampus and prefrontal cortex. But if you’re an artist or a musician or someone who just wants to think a bit more creatively about a problem, it might be helpful. THC may loosen up your thinking, allowing your imagination to engage more readily outside the box. The neural mechanism underlying that is difficult to pinpoint. Creativity is still a slippery concept in science. There’s a theory that drugs that disrupt a network of interacting brain regions called the default mode network, the DMN, do increase what’s known as “divergent thinking,” thought of as one measure of creativity. However, there aren’t enough studies to say definitely whether cannabis disrupts the DMN in a way similar to hallucinogenic drugs such as LSD, ayahuasca, and magic mushrooms.

My friend said he drives better while high. Is he lying?

Almost certainly. Cannabis has a negative effect on motor function, which makes getting behind the wheel while stoned a very bad idea.