Aidan:
Hello and welcome to episode 154 of the Ideal Nutrition podcast. My name is Aidan Muir and I’m here with my co-host, Leah Higl and today we are going to be talking about how much caffeine affects sleep. A large portion of this episode is going to be based off of a review titled, The Effect of Caffeine on Subsequent Sleep and a Systematic Review and Meta Analysis.
The reason I’m mostly focusing on that is because it is the simplest way to cover this topic. There’s so many things you can look at. But the best bit about this review is it used a lot of very specific numbers. And we know that caffeine is very individualised, but I like to have specific numbers to kind of draw from so that we can use individualisation after having an awareness of being like, this is what the average is. If you think you metabolise it slightly faster, then you can obviously just account for it based on that. But having awareness of averages, I think helps with how we can plan out our nutrition strategies.
Leah:
Totally. So we’re going to start with looking at this overall without context. So like a little bit of a broad overview. So this review featured 24 studies in total, and they found that within those studies, on average, caffeine did reduce sleep duration by 45 minutes and sleep efficiency by 7%. Obviously that is not overly helpful without the context of how much caffeine was consumed in each study, the timing of the caffeine and all the individual variation that can happen in regards to metabolising caffeine. So breaking down all 24 studies would take us a very long time.
So we’re not going to go through every single study and individually say what they found because it would be too much for a podcast episode. But we’re going to go through a few things that will make this slightly more relevant and start adding some form of numbers to it.
Aidan:
So before getting into the rest of the review, there’s one factor that should be relevant from the individual perspective is the half -life of caffeine. So the half-life of caffeine is around five hours. You’ll find different numbers out there that people will say, but I say around five hours. So that means on average it takes around five hours to be half out of your system. That is where the individual variation comes in, because half-life for caffeine ranges from 1.5 hours to 9.5 hours based on the individual. So somebody could take one and a half hours to get half out of their system. Somebody else theoretically could take nine and a half hours to get half out of their system. That sounds unfortunate, like that’s a very long time.
But there are a lot of people who like, will find that they are super sensitive to caffeine, it does affect them for a long period of time. But I want you to have the context of that going into the rest of everything we’re about to talk about, because we are going to talk about a lot of averages. Although one quick caveat that I add on that is there are a lot of people who have caffeine right before bed or within a few hours of going to bed and they’re like, this doesn’t affect me because of individual variations, stuff like that.
Statistically speaking, the number of people who do say that, it can’t be the case. We can’t all be hyper responders or we can’t all be people who have 1.5 hour, like kind of half life. But it’s useful to know that the range does exist because there will be some people who are towards that end of the spectrum as well.
Leah:
Especially with sleep efficiency and like quality of sleep, I feel like that’s a very hard thing to gauge, especially if you’re habitually doing the same thing. So it’s like, how do you know that it’s like a 50 versus not?
Aidan:
Like using a specific example, I’m sure everyone’s come across this, but our clients who I’ve spoken to who have struggled with sleep and I’ve started talking about caffeine and they’re like, no, it doesn’t affect me. And I will be like, have you had a day without caffeine in the last three years? And they’re like, no. And like, once again, I’m trying to say this like from like a truly non -judgmental perspective, like truly just being like, if it’s been three years, like it’s worth a crack. Like it’s worth just, just trying and just seeing if there is a difference. Like maybe there’s not, but it’s worth trying.
Leah:
I’ve definitely been that person that was a bit delusional for a while about how caffeine didn’t affect me, but it definitely did. But I think that’s just a common thing. But returning back to the review and the averages and being more number specific, it included really interesting information on how far away from going to sleep caffeine would need to be consumed to have minimal impact on sleep quantity and quality. And they found that to avoid impact on total sleep time, a coffee containing 107 milligrams of caffeine should not be consumed within nine hours of going to bed.
A serve of pre-workout, which they counted as 217 milligrams of caffeine, they concluded that it should not be consumed within 13 hours of going to bed to have no impact on sleep in total. Which when you like take an actual moment to think about like nine to 13 hours. So that means if you went to bed at 10.30 PM, you would need to avoid taking that pre-workout that was like 200 milligrams of caffeine from like, you’d have to take that before 9.30 am for it to not impact your sleep at 10 .30 pm. Which I think is just crazy and a statistic that many people wouldn’t expect to see.
Aidan:
It’s also why I love this review and it’s part of why I referenced this review of Fabian because those obviously just averages individual variation, etc, etc. Yeah. But it’s also like, it’s one thing to be like having caffeine late in the day will affect your sleep. It’s another to be like, if you have a relatively high dosage of caffeine at 10am. There’s a chance that it affects your sleep if you got to bed at like 10pm or something like that.
Leah:
Insane. Those stats don’t even account for caffeine stacking either. So something that a lot of us will do is we’ll have a coffee in the morning, maybe like 7.30 and then add like a pre-workout or an energy drink later in the day or even just like mid morning. Like your total amount would be higher. Therefore like that higher dosage would stay in your system for longer and therefore you’d have to like consider that total amount and it’s half life and potentially having an impact on sleep like way, way later in the day.
From a positive perspective though, something a little bit nice is that the review found that drinks with low caffeine content, so things like tea had minimal to no impact on sleep when consumed in isolation. So you could probably get away with things like tea or things like coke no sugar and those kinds of things that are like pretty low in caffeine but still have some caffeine content.
Aidan:
Yeah, and once again, individual variation there, like there will be people who might notice that, but these are just averages and on average, most people didn’t seem to have an impact there. I was trying to like look for flaws here and stuff like that. Somebody I did see somebody bring up them like could be a little bit relevant is we know in almost all caffeine research, but not all, but a lot of caffeine research, people have to refrain from having caffeine for a period of time prior to the study. So they arguably might be a little bit more sensitive to it. How much of a difference would that make for stuff like this? It’s hard to say, but it is something worth knowing when, when like looking at all of this research, basically.
Continuing through with like how I’d interpret this research, once again, just doubling down these numbers are simply averages. They could be pretty irrelevant to you or they could be more relevant than you think. Like let’s just say for a second that you do respond to caffeine or you metabolise caffeine twice as quick as the average person. That still means like if you’re having pre-workout after 5pm it’s still going to be affecting your sleep, like it’s still worthwhile.
We know that high doses of caffeine late in the day are likely to impact sleep pretty noticeably in almost everybody, even with these individual responses. And we also know sleep is far more important than the performance benefit of caffeine. There could be a lot of things you could go through here being like, what if somebody just did not want to try it all on caffeine, hype them up? Like there can be exceptions here maybe, but definitely the later in the day and the higher the doses of caffeine, the more negative of an impact it is going to have on your sleep.
There is a classic example. I don’t know if this client listens to the podcast, but she sent me a text the other day. So we met how she was trying later today and she was having, or later that day at 5pm and she was going to have pre-workout before it. I was like, please don’t. Like as a general rule, I have a rule that like after 2pm probably don’t have caffeine. There are exceptions to that, but like that’s my general rule. But she’s like, but I’m pretty tired. And I’m like, it just creates a cycle though. You’re going to get worse sleep and then so on and so forth. Sleep is far more important from so many angles, you know it benefits so many things like injury recovery, such reduction in the risk of injury, potential for body composition changes, making it easier to stick to nutrition and training plans. There’s so many benefits to it, so it makes sense to try to prioritise that as well.
Leah:
Yeah, as a little bit of a summary, I’d say that caffeine, like based on this review and the research that we have, like caffeine definitely does impact sleep quality, sleep quantity. Whilst there is individual variation, it probably impacts people more than they realise in reality, because the clients that I work with often will have caffeine in the morning, caffeine midday, caffeine later in the day before their training, and state that, you know, they don’t really feel like it really impacts their sleep a lot. But based on this research, we can kind of conclude that it probably does and are we perpetuating this cycle of like fatigue and needing more caffeine and kind of building on that?
Aidan:
This has been episode 154 of the Ideal Nutrition podcast. Once again, I just want to double down on plugging the Insights with Ideal Nutrition podcast that we have. It’s our other podcast as an interview based one. Our co-worker Hannah Mills, she is interviewing a bunch of nutrition experts. If you like the type of stuff that we put out, I think you would very much like that. So I would definitely encourage listening to it.