(silence) Does marijuana disrupt sleep? - Yeah, it does. And there's a pretty good amount of data on, so we can break sort of cannabis down into two of its key ingredients. We've got THC, tetrahydrocannabinol, and we've got CBD. And CBD is sort of the less, what we think of as the non-psychoactive component.

In other words, when you take CBD, you don't get high. If you take THC, you can get high. That's the psychoactive part of the equation. - Are both considered sedatives in the technical sense? - No, they're not. Neither of them have that class right now. THC seems to speed up the time with which you fall asleep.

But again, if you look at the electrical brainwave signature of your falling asleep with and without that THC, it's not going to be an ideal fit. So you could argue it's non-natural, but many people use THC for that fact because they find it difficult to fall asleep. And it can speed the onset of at least non-consciousness, I guess is the best way of describing it.

But there are problems with THC and there are twofold. The first is that it too, but through different mechanisms, seems to block REM sleep. And that's why a lot of people when they're using will tell me, look, you know, I definitely, I was dreaming, I don't remember, you know, many of my dreams.

And then when they stop using THC, they'll say, I was having, you know, just crazy, crazy dreams. And the reason is because there is a rebound mechanism. REM sleep is very clever. And alcohol is the same way in this sense. It's the same homeostatic mechanism. Some people will tell me, look, if I have a bit of a wild Friday night with some alcohol, you know, maybe I'll sleep late into the next morning and I'll just have these really intense dreams.

So, and I thought I wasn't having any REM sleep. Well, the way it works is that it's during in the middle of the night, really, when alcohol blocks your REM sleep. And your brain is smart. It understands how much REM sleep you should have had, how much REM sleep you have not because the alcohol has been in the system.

And finally, in those early morning hours, when you're getting through to sort of, you know, six, seven, 8 a.m. - REM like crazy. - All of a sudden, your brain not only goes back to having the same amount of REM it would have had, it does that, plus it tries to get back all of the REM sleep that it's lost.

Does it get back all of the REM sleep? No, it doesn't. It never gets back all of the REM sleep, but it tries. And so you have these really intense periods of REM sleep. Hence, you have really intense, bizarre dreams. And that's what happens also with THC. You build up this pressure for REM sleep, this debt for REM sleep.

Will you ever pay it back? It doesn't seem as though you get back everything that you lost, but will you get back some of it? Yes, the brain will start to devour more because it's been starved of REM sleep for so long. But one of the bigger problems with THC that we worry about is withdrawal dependency.

So as you start to use THC for sleep, there can be a dependency tolerance. So you start to need more to get the same sleep benefit. And when you stop using, you usually get a very severe rebound insomnia. And in fact, it's so potent that it's typically part of the clinical withdrawal profile from THC, from cannabis.

- And there's anxiety withdrawal. I don't ask anybody to change their behavior. We just, as you said, we try and inform people about what the science says and let them make choices for themselves. People who are regular pot smokers, that many will insist they're not addicted. And maybe indeed they don't actually follow the profile of classical addiction.

I don't know. I'm guessing some do, some don't. But if you ask them, well, what if I took away all marijuana consumption for, I don't know, two weeks? That thought scares many of them. And many of them will experience intense anxiety without marijuana, which speaks to perhaps not addiction, but a certain kind of dependency.

And again, I know many pot smokers, some of whom have jobs that are quite high-performing and they manage. - Here in Berkeley, I don't know any of those. - Yeah, none of those, right. What about CBD? I mean, we hear so much about CBD. I've been a little concerned about the fact that the analysis of a lot of CBD supplements out there has confirmed that much like with melatonin, the levels that are reported on the labels in no way, shape, or form match the levels that are actually contained in the various supplements.

Sometimes the levels are much higher than they're reported on the labels. Other times it's much lower. What does ingesting CBD do to the architecture and quality of sleep? - Right now, I don't think we have enough data to make some kind of meaningful sense out of it. I think the picture that is emerging, however, is probably the following.

Firstly, CBD does not seem to be detrimental in the same ways that THC is. So we can start by saying, does it create potential problems? Not of the nature necessarily that we see with THC, but the devil is a little bit in the details from the data that we do have, and it comes onto your valid point of purity.

At low dose, CBD can seem to be wake-promoting. So in lower doses, let's say sort of five or 10 milligrams, I'm trying to remember some of the studies off the top of my head. There, it actually may enhance wakefulness and cause problems with sleep. It's only once you get into the higher dose range that there seem to have been some increases in sleepiness or sort of sedation-like increases.

And that's usually, I think, above about 25 milligrams, as best I can recall from the data. And then when we look in animal models, you typically see the same type of profile too. So then the question becomes, and now again, you just don't know about purity. It's very difficult.

Although I think, and again, I'm not a user, not necessarily because I have anything against it. It's just that's not necessarily my cup of tea. There are some firms that are now doing third-party independent laboratory tests. I don't know how gamed that is, so I've got no sense of it.

- No, I think some supplement companies are quite honest and accurate about the amounts of various substances that are in other products, and some are not. And I think there's just a huge range. I think the FDA is starting to explore CBD. There are, certainly I saw some grant announcements to explore the function of CBD.

Most of the work on CBD is being done by the general public, ingesting it and seeing how they feel. - Right now, if we were to, and I'm not making this statement, I don't think anyone could make the statement now, but if it ends up being that CBD is potentially beneficial for sleep, how can we reconcile that mechanistically?

And I think there are, to me at least, there are at least three candidate mechanisms that I've been exploring and thinking about. The first is that it's thermoregulatory. And what we found in some animal models is that CBD will create a profile of hypothermia. In other words, it cools the body, the core body temperature down, and that's something that we know is good for sleep.

The second is that it's an anxiolytic, that it can reduce anxiety. And that data is actually quite strong, even with some functional imaging work that's been coming out recently, showing that one epicenter of emotion called the amygdala deep within the brain is quietened down with CBD. So I think that's at least a second non-mutually exclusive, you know, possibility.

I think the third is some recent data that's come out that was suggesting that CBD can alter the signaling of adenosine. So it doesn't necessarily mean that you produce more adenosine, but what it can do is perhaps modulate the sensitivity, perhaps, of the brain, so that the weight of that same adenosine is weightier in its brain signal, and therefore it creates this stronger pressure for sleep.

So I think these are all tentative mechanisms. I think any one of them is viable. I think all three are viable together. But right now, I think, does that sort of help think through the tapestry of THC and CBD? - Yeah, very much so. And actually, it's a perfect segue from we've talked about caffeine, alcohol, THC, and CBD as sort of, we framed them anyway, as things that done in moderation at the appropriate times are probably okay for most people.

Certainly not for everybody. There will be differences in sensitivity, but that done at the incorrect times, and certainly in the incorrect amounts, will greatly disrupt this vital stage of life we call sleep. you