Caffeine Deep Dive
I don't know many people who don't partake in at least a little caffeine.
Most of that caffeine is consumed during the first few hours of the day. Although for many of us with ADHD, we find that it's something that we reach for far more frequently.
To first understand how caffeine works. We also need to understand adenosine, which acts as an inhibitory neurotransmitter in our brain, it acts as a central nervous system depressant and inhibits many processes associated with wakefulness. As the day goes on and the levels of adenosine in our brain increase so do our levels of sleepiness. This is called sleep pressure. So the longer we've been awake, the more sleep pressure we feel.
When we're asleep, our adenosine levels drop and so if we've got a full night's sleep, when we wake up we are ready to start the process over again. What caffeine is able to do is bind to the adenosine receptors in our brain, preventing adenosine itself from binding to them.
This means that while caffeine is in our system, we're preventing ourselves from experiencing the effects of adenosine. and so we're also not building up that sleep pressure.
It should be noted, however, that this does not prevent the buildup of adenosine. Just the ability for it to bind to adenosine receptors. This means when that caffeine wears off. We can experience a crash where all those receptors now have a place that they can bind.
So while caffeine can promote wakefulness, it's only as a stop-gap measure, we're still going to need to sleep and that crashed and caused an even worse state of sleepiness. Once the caffeine wears off.
Caffeine can also increase dopamine levels by slowing down the rate of dopamine reabsorption. And by slowing down this rate, we end up with more available dopamine in our systems.
So caffeine peak effect comes about one to two hours after it's ingested. Although we usually start feeling the effects of caffeine within 10 minutes. Caffeine will then stay in our system for quite a while.
Caffeine has a half-life, which is the amount of time for the body to eliminate half of one dose is three to seven hours. That variance is going to depend on your tolerance to caffeine, as well as a number of other factors like age, weight, health, sex as well as how well your body can metabolize caffeine.
Additionally, any other substances you have in your body can affect this. Tobacco reduces the half-life by about 50% while oral contraceptives can increase that half-life.
Understanding how half-life works is important to understand how much caffeine we're going to have in our system at any given time. If we just take the regular half-life of caffeine and I'm going to go with about five hours here to split the middle here and say, drink a single eight-ounce cup of coffee. We start with roughly 80 milligrams of caffeine.
What that five-hour half-life means is that if we have a cup of coffee at nine eight, We've got about 40 milligrams of caffeine in our system at 2:00 PM. What this does not mean, however, is that 7:00 PM we've cycled through another 40 milligrams of caffeine. Instead, we're looking at the half-life of that remaining 40 milligrams, which means at 7:00 PM, we've still got about 20 milligrams of caffeine in our system.
It's going to take roughly four to five half-life cycles to get about 94-97% of the drug out of your system. It might seem counterintuitive, but that's just how our body processes these substances. Although if you do take a large enough dose, it could take longer for the drug to completely be out of your system.
Caffeine is considered generally safe with a dose of about 400 milligrams a day, which is about five, eight-ounce cups of coffee.
All right. Let's talk about some of the benefits of caffeine. So we already know that it creates this state of wakefulness, and that can be accompanied by some euphoria due to the increases in dopamine as well. Caffeine also has a number of performance-enhancing effects. On the cognitive side of things. We have better reaction times. Again, wakefulness with studies, showing things like shift workers who use caffeine, make fewer mistakes that could result from drowsiness. You also have better concentration and better motor coordination.
Caffeine can also enhance your physical performance with increases in basal metabolic rate. you can have a delayed onset of muscle fatigue, which means you can just exercise longer. There are some studies showing that caffeine can increase muscular strength and power and then there's also an interesting effect that caffeine consumption before exercise can reduce your perceived exertion, which means that if you're trying to exercise to exhaustion, you can perform significantly more exercise than you would without caffeine because caffeine extends that time until we reached that perceived fatigue feeling.
There are also some studies showing that a moderate dose of caffeine has been associated with reduced symptoms of depression and a lowered risk for suicide.
Now with all that said, caffeine can also have some side effects as well.
Some people experience sleep disruption or anxiety. It can produce a mild form of drug dependence stopping caffeine, absolutely causes withdrawal symptoms with sleepiness, headaches, and irritability.
Physical effects include things like the jitters. You can have gastrointestinal problems, high doses can increase risks of things like hypertension and can give you an increased heart rate.
but really it's big as effects have, to do with your sleep. Some people experience increased sleep latency, meaning how long it takes you to get to sleep. Also cases of insomnia. And if you have caffeine in your system, while you're sleeping, it can reduce the quality of that sleep.
Caffeine can also lead to risky behaviors, like loss of inhibition and impulsivity, which is important to consider when you have ADHD and you might already have those symptoms.
And you might be asking, well, can you have too much caffeine? And you can absolutely overdose on it. And you can even take a lethal dose if you have too much caffeine. although that's a hard limit to reach, it's about 75 to a hundred cups of coffee.
So that's a lot of coffee, but if you take pure caffeine, it's actually quite easy to hit that limit.
So with all that, it's also important to think about how caffeine interacts with ADHD. And while there are some studies, there's also still a lot we don't know on this subject.
One thing I've seen pop up over and over again is that for people with ADHD, caffeine can make them feel sleepy. However, there is no science to back this up. Now I want to be clear here. This is because there are no studies on this specific effect. So when I say there is no science, it's because there's literally nothing on the subject.
But this highly anecdotal aspect of caffeine is worth considering because of how ADHD can be treated with stimulant medication. One clear indication with caffeine. One of the clearest indications with caffeine is that many people with ADHD attempt to self-medicate with caffeine, intentionally, or unintentionally, because it's also a stimulant and very easy to get.
Let's take a quick time out here. I'm in no way, advocating that you should seek to treat your ADHD with caffeine. While caffeine can clearly help with some aspects of ADHD, there just isn't enough data to suggest that it's an effective treatment. As well, since it's so easy to build up a tolerance to caffeine, it quickly becomes unmanageable and has considerable side effects at a high dose. While I can certainly see caffeine being part of someone's daily routine, it should not be anyone's primary way of managing their ADHD.
All right, let's get back into this.
One piece of anecdotal evidence I found was that many people report their need for caffeine diminishes once they start taking stimulant medication. This makes complete sense, but again, this is completely anecdotal - there still needs to be a lot of research done on how caffeine and ADHD interact. It's also important to get to there that many of us with ADHD already have trouble sleeping and that caffeine can easily disrupt your sleep.
Of course, we just discussed how caffeine can make many of us with ADHD feel sleepy. But the real question here is the quality of that sleep. Even among neurotypicals, many people are able to fall asleep with caffeine in their system. Remember caffeine only blocks the adenosine receptors. If we already have sufficient buildup of adenosine caffeine, isn't going to actually wake us up anymore, we'll just be sleepy faster.
So while some of us can still get to sleep with caffeine in our systems, there is ample evidence that it still affects the quality of that sleep. With caffeine in our system, we see a notable decrease in the amount of slow-wave sleep we get. And another study found that consuming caffeine as early as six hours before bed can reduce total sleep by about an hour.
What we can take from this is that we really have to watch the timing of our caffeine. As we discussed with the caffeine half-life, caffeine can remain in your system well after its initial effects have worn off. The best course of action here is to consider a caffeine curfew. That is a cutoff time where we're gonna stop consuming caffeine.
This is going to be different for everyone, but with that five-hour half-life, most of us are going to want to make sure that we're cutting ourselves off, probably at least 10 hours before bedtime. Of course, this is going to depend on how well you metabolize caffeine in your system and your own personal tolerances.
Some studies have found that adolescents with ADHD are far more likely to use caffeine in the afternoon and evening as a way to self-medicate. While the study was focused on adolescents, I'm sure many of those habits continue into adults. So for many of us, we're consuming a lot more late-day caffeine than our non-ADHD peers. An interesting note here though is that it's not clear whether this is a cause or an effect.
Yes, caffeine absolutely affects our sleep, but caffeine is one of the first things many of us reach for when we're suffering from a lack of sleep. So there's a bit of a chicken and an egg. Is it the poor sleep from ADHD causing the need for caffeine in the afternoon and evening? Or is it the caffeine that's causing poor sleep? I'd contend, it's a bit of both and I'd still recommend against late-day caffeine consumption if you can.
I also want to point out that one of the most common comorbid conditions with ADHD is substance use disorder. Those of us with ADHD are about twice as likely to find ourselves battling with substance abuse or dependency.
Caffeine is absolutely a drug we can abuse and it can have some serious side effects. So it's important to understand how we're using this drug and being responsible when we do partake in it.
This Episode's Top Tips
Caffeine is a psychoactive drug whose primary mechanism is binding to adenosine receptors in the brain. The buildup of adenosine in our system is what makes us sleepy, so by binding to these receptors caffeine is able to keep us awake.
Caffeine has a host of benefits but having too much caffeine near bedtime can affect our slow-wave sleep and reduce our total amount of sleep.
There is still a lot of research that needs to be done on the interaction between caffeine and ADHD but it is clear that many people with ADHD attempt to self-medicate with caffeine.
