Episode 114 - Caffeine and Sleep - New Research Update!

Caffeine and Sleep - New Research Update!

Did you know that 20-45% of the global population is sleep deprived?!

We know how important sleep is for us and the many negative outcomes associated with insufficient sleep. We also know that caffeine intake too close to bedtime affects our subsequent sleep - both the quality and duration. But what we didn’t know exactly until recently was how much caffeine is problematic and how close to bedtime is too close.

Introducing a NEW research study that has clearly quantified both caffeine dose and timing to ensure our sleep is not affected. 

Tune in to dive into the results and recommendations to help you perform at your best in the sleep department! Without having to ditch your beloved cup of coffee.

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Gardiner, C., Weakley, J., Burke, L. M., Roach, G. D., Sargent, C., Maniar, N., Townshend, A., & Halson, S. L. (2023). The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Sleep medicine reviews, 69, 101764. https://doi.org/10.1016/j.smrv.2023.101764

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Episode Transcription

Episode 114: Caffeine and Sleep - New Research Update!

Taryn Richardson  0:00

Welcome to the Triathlon Nutrition Academy podcast. The show designed to serve you up evidence-based sports nutrition advice from the experts. Hi, I'm your host Taryn, Accredited Practicing Dietitian, Advanced Sports Dietitian and founder of Dietitian Approved. Listen as I break down the latest evidence to give you practical, easy-to-digest strategies to train hard, recover faster and perform at your best. You have so much potential, and I want to help you unlock that with the power of nutrition. Let's get into it.

Taryn Richardson  00:41

Did you know that 20 to 45% of the global population is sleep deprived? Isn't that crazy? That is so many people that aren't getting enough sleep. And that's a lot considering how much insufficient sleep or sleep deprivation is linked to negative outcomes. We've got obviously impaired mental function, I don't know about you, but my brain doesn't work particularly well and I'm tired. Your mood is definitely impacted, which again, if you've been tired for an extended period of time, you'll know what I'm talking about. But also you have an increased risk of illness and an increased risk of injury. It can also be a struggle to manage your body composition. And obviously, productivity is pretty low. But then chronically, this sleep deprivation and sleep whole can lead to mental health disorders and lots of cardio metabolic disease as well, which is really, really scary. So there's lots of things that are set up to try and help us get better sleep as a result of that.

Taryn Richardson  01:45

Now, despite what you might think the actual recommendations for sleep are seven to nine hours every single night. And I often hear that people think that they survive or wear with a badge of honour, that they only need five hours of sleep a night or six hours of sleep per night. And it's just ridiculous. I hate having arguments with people about that. Why would you shoot yourself in the foot by not doing the best things you can for your body and your overall health. And feeling like sleeping is a waste of time. Now obviously, how much sleep you need is very individual, but four, five, or even six hours a night is not enough, particularly for somebody that's really active. Some people need more than seven to nine hours of sleep a night. I know a lot of high level athletes, and particularly younger growing bodies that need 10, 11, 12 hours of sleep some nights when they're in big training volume.

Taryn Richardson  02:42

So it's really important that we prioritise our sleep so that we're getting good quality and duration for what our body needs. Personally, I'm a nine hour sleeper. And while a lot of people over my professional career have argued that's a complete waste of time, I am so much more productive and really effing efficient in my waking hours. And I know that I feel like crap, if I get less than eight, which has been really hard as a parent of little people. Because it I will often get less than eight. And I don't feel very good for that. So because we know how important sleep is there are actually lots of tools and strategies that have been developed to help people get better sleep. And we're talking about quantity here. So total number of hours. But also the quality is really important. You can be in bed for nine hours and have a really crappy quality night's sleep.

Taryn Richardson  03:37

Now one of the things that I'm interested in from a nutrition perspective is caffeine, and understanding how to manage that to make sure we're not affecting our sleep, both quality and quantity. And the timing that that needs to kind of be cut off by caffeine is a very socially acceptable drug. It's actually a psycho stimulant. And it is the most research supplement that exists. 80% of the world consumes caffeine in one form or another. Now that doesn't have to be coffee. I immediately encoded coffee when I think caffeine, but it could be tea. It could be caffeine and gels or blocks or sports drinks. Or it could be energy drinks that a lot of people are consuming these days that have a very high amount of caffeine. It could be things like caffeine, tablets, and pills that are a caffeine supplement.

Taryn Richardson  04:28

So 80% of the world consumes some form of caffeine, which is pretty crazy. Now it works by stimulating the central nervous system. It helps to reduce our perception of fatigue and effort, but also reduces our perception of sleepiness, which is why a lot of people are habitual caffeine users, they get up and they feel tired and so they drink some coffee or a cup of tea or have some form of caffeine to help them get over that slump. Caffeine does have what's called a long half life. So It's very individual, but it's around three to six hours, some people shorter, some people even longer, which means that over a certain period of time, half of that caffeine dose is still in your system. So say you had 200 milligrams of caffeine and assuming your half life processing time is five hours, five hours later, 100 milligrams of that caffeine is still in your system.

Taryn Richardson  05:25

So one of the strategies that you can implement to help manage your sleep and not be affected by caffeine with sleep is to keep it as far away from it as possible. So I've always recommended athletes not consumed caffeine after about lunchtime. And that's not based on anything other than just practical experience. Because we didn't actually know the specific quantifiable doses of caffeine and timing, to give specific recommendations around that, to not affect our sleep, and also your ability to fall asleep.

Taryn Richardson  05:57

So I was really excited to see a new research paper that I just read all about the effect of caffeine on our subsequent sleep. It's a big systematic review and meta analysis. It was published in 2023 so it's hot off the press. I'll link it in the show notes if you do want to nerd up and go and read it. But a meta analysis in particular is the highest level of research caliber, it's nice and robust. And I've read through the methods and really understood deeply what type of studies they've pulled for this meta analysis. So there was 24 studies in total that they collected data on, and it was done in healthy adults aged 18 to 65 was their range. So it's not done specifically in triathlon, it's not done specifically in an athlete population, just general healthy adults. 

Taryn Richardson  06:47

And to save you nerding up and reading it, this is their key findings, which is really, really exciting, because we can now quantify that advice around caffeine dose and timing so that we're not affecting our sleep that night. So they found that caffeine consumption reduced total sleep time by 45 minutes and sleep efficiency by 7%. With an increase in sleep onset latency of nine minutes, so it took you longer to get to sleep. And then you wake up after sleep onset of 12 minutes. So you're not actually getting into sleep particularly effectively, and then you're waking up afterwards, just by consuming caffeine. Now the duration and the proportion of light sleep increased with caffeine intake, so you're in a lighter phase of sleep for longer. And the duration and proportion of our deep sleep decreased with caffeine intake. So that quality of sleep is reduced with caffeine. Now the closer to bedtime and the higher the caffeine dose, the greater the reduction in total sleep time.

Taryn Richardson  07:57

So it's a big vicious circle. You have a poor sleep, you consume more caffeine to stimulate your wakefulness, get you out of that hole and that impacts your subsequent sleep the next night, so that your duration of sleep is shorter. And the quality of that sleep is not as good compared to if you didn't have caffeine. And I see that with people a lot. It's a drug and we kind of get addicted to it. And we feel like we need it to get awake in the morning. And then we build a tolerance to it. And our total amount of caffeine intake we consume in a day just keep slowly building over time, until you're at the point where you're at two, three, maybe four cups of coffee or tea or something in a day. And you feel like you need it because we're then affecting our sleep the next night and it's not as great even though you might feel like you did go to sleep, we're in a light phase of sleep for longer. And we're not in that really good deep quality sleep where a lot of our recovery pathways occur. That's really cool research to understand what is actually going on, because we've always known that caffeine affects sleep, but the paper quantified exact doses of caffeine and timing away from sleep to understand where is our cutoff point for it being affected versus not being affected. So I've got some good recommendations for you.

Taryn Richardson  09:22

Now, you know, I love me a good cup of coffee, coffee is life. So take it or leave it. But there's some beautiful evidence based guidelines to guide your caffeine consumption to maximise your sleep quality. So if you want to avoid the reduction in total sleep time, then a cup of coffee which based on their analysis was 107 milligrams of caffeine per 250 mil cup so your coffee might be weaker than that or it might be even stronger than that. But that dose of caffeine 107 milligrams needs to be consumed at least 8.8 hours prior to bedtime. So if you go to bed at nine o'clock at night because you're a triathlete, then that means no caffeine after midday, if you go to bed earlier than that, you need to bring that forwards. And if you go to bed a bit later than that, like if you're a 10 o'clock 11 o'clock at night sleeper, then you could shift it back a little bit. But 8.8 hours before bed, is your cut off where that dose of caffeine 107 milligrams is going to start affecting your sleep. 

Taryn Richardson  10:32

Now, if we want to increase the dose, they found that a standard serve of a pre workout supplement, which was 217.5 milligrams, should be consumed at least 13.2 hours prior to bedtime. So if you go to bed at nine o'clock at night, you can't have that amount of caffeine, no later than 8am in the morning. And then low doses, so 47 milligrams of caffeine per 250 meals in something like a week black instant coffee, that didn't really find a clear effect, or a reduction in total sleep time. So that might be something that you could have, and it not negatively impact your sleep. I'm not saying that you should.

Taryn Richardson  11:19

Now of course, there's going to be individual because we have higher caffeine processes, like faster processes, slower processes, we have caffeine non responders. So that's some really good data to work from and to pin from. And then you need to understand how your body works and what works for you. But I really love the vicious cycle thing. And thinking about that, so that if you do have a really poor night of sleep, let's not try and fix that with more caffeine, just, you know, write that day off as a not particularly effective, not particularly productive day where you maybe just feel really flat, so that you're not impacting that night's sleep further. Because we know that even mild sleep restriction, so about an hour, that's going to disrupt your emotional regulation and impair your cognitive function, so your brain function and your behaviour of as little as an hour in one night. And then if you compound that over time, so over 14 days, or two weeks of one hour, a night, less sleep, that effect is equated to an entire night of sleep deprivation.

Taryn Richardson  12:33

So we need to get off that rat wheel, if you are finding that you becoming more reliant on caffeine to get you through the day, because it is affecting us negatively. And the more that happens, the worse that's going to get. Now, I also want you to think about applying that practically to your training, if you're practicing strategies like caffeine and training, but also race day, if you're doing a longer course event and you're having caffeine, maybe on the bike or the run is that before midday, and you go to bed at nine o'clock that night, maybe you go to bed earlier that night because you're shattered.

Taryn Richardson  13:10

But think about that timing of that dose of caffeine and you're racing, and where that sits based on where you're going to sleep. Because I know a lot of people that I've seen a lot of people consume way more than 107 milligrams of caffeine in a serving or in a race depends on your requirements. We're not going to dive into that in this episode, this one is purely about sleep. But being mindful of that, and a lot of people like Oh, who cares, my race is finished, I don't care if I sleep the next night or not, I'll be so tired that I'm just going to go to bed anyway. But know that your total duration of sleep that night, and the quality is not going to be great. And so your recovery is affected. And that's really important to understand because we often just stop thinking about ourselves and our body and our nutrition once we crossed the finish line. 

Taryn Richardson  14:04

And I love to teach my Academy athletes to extend their thinking beyond beyond just that immediate post exercise recovery window into multiple days after and like the week after. Because sleep is our ultimate form of recovery. Plus, we also need to make sure we're putting the right building blocks of nutrition back in. A lot of athletes will find themselves sick or injured a couple of weeks after a race and you don't equate the two things together because it is so far away. But if you've ever experienced that 2,3,4 weeks after a race, you're really sick, you've picked up a cold or a flu or you've got niggly injuries, then that has been impacted by race day. And we need to align them. So thinking about high doses of caffeine on race day not having great sleep to recover on race evening, we need to do as much as we can to set ourselves up to recover as best as we possibly can.

Taryn Richardson  15:05

And knowing that that sleep quality might not be great, you're going to wake up the next morning and probably feel pretty tired. Yes, you've just done a triathlon, but also your sleeps not probably been that great if you've had a fair whack of caffeine close to bed. So just food for thought, I really loved reading this paper. I know that sounds super nerdy, that is what I did with my Wednesday night like a loser. But it's really good research that we haven't seen before to quantify doses of caffeine and duration of away from sleep. So some nice little guidelines there to guide us. Now another thought, if you're a habitual caffeine user, you do seem to adapt to your caffeine intake. This is come from rodent studies, it's not actually been established in humans, but they found that the more caffeine they gave them and you know, more consistent they were with that over the time. They seem to just adapt their whole systems and pathways for caffeine regulation in a way. 

Taryn Richardson  16:06

So I say that because I know a lot of people are heavily addicted to caffeine. And you might be like, I'm fine. Like, I'm totally fine. I go to sleep fine, I wake up fine. I drink my four cups of coffee a day, I'm all good. But I would encourage you to think about the dose and think about the timing. Because we all could do with better sleep. If 20 to 45% of the global population is sleep deprived. Let's try and do something to fix that. So if you do want to dive into this new research update, I will link it in the show notes. It is pretty heavy going I'm not gonna lie, but some pretty sweet recommendations off the back of it and relatively hot off the press. It was published back in February 2023. So thanks for nerding out with me today. I hope you enjoyed that. If you want more research updates like this, please let me know.

Taryn Richardson  17:04

Thanks for joining me for this episode of the Triathlon Nutrition Academy podcast. I would love to hear from you. If you have any questions or want to share with me what you've learned, email me at [email protected]. You can also spread the word by leaving me a review and taking a screenshot of you listening to the show. Don't forget to tag me on social media, @dietitian.approved, so I can give you a shout out, too. If you want to learn more about what we do, head to dietitianapproved.com. And if you want to learn more about the Triathlon Nutrition Academy program, head to dietitianapproved.com/academy. Thanks for joining me and I look forward to helping you smashed in the fourth leg - nutrition! 

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