 Hey everybody, Dr. O here. So if you want better sleep, you have to avoid caffeine late. So these next two videos are two of the most important in the entire course in my opinion. We need to try to avoid caffeinated soda, tea, coffee, and chocolate late. The only problem is late can mean different times to different people. Caffeine is often the cause of our sleep issues, but we treat it like the cure. Let's start by actually looking at how caffeine works. To understand caffeine, we have to understand adenosine. We talked about adenosine back in the video about napping, but one of the main signals that builds up the sleep pressure needed to fall asleep is the buildup of this molecule in our brain called adenosine. Adenosine counts how much energy you have used to know when it's time to recharge. I love that. That's why I think about adenosine like the sand in an hourglass. Once the top half of that hourglass empties, your brain is now full of adenosine and your brain says, okay, now it's time for sleep. We have to flush this adenosine out, so then we flip it over and do the same thing tomorrow. Basically, we need eight hours of sleep to flush out the adenosine buildup from 16 hours of being awake. If you're wondering if maybe you've taken biology classes and you're wondering why adenosine sounds familiar, it's because adenosine triphosphate or ATP is the energy that our body uses. It's literally a waste product of our metabolism. The more time you've been awake, the more adenosine you've built up. Adenosine levels increasing in the brain are making you tired. We talked about how naps will flush adenosine out of your system, but what's caffeine do? Caffeine actually tricks your brain by plugging adenosine receptors. It makes it so your brain can't count how much adenosine is in the brain. Caffeine decreases the amount of adenosine that your brain can see. It tricks your brain into thinking you haven't been awake as long as you actually have. It's like your brain's going, wait a minute. I could've sworn we've been up 16 hours, but now it looks like we've only been up for 12 hours. I guess we shouldn't be tired and it shouldn't be bedtime. My bad, right? That's what it does. It fools your brain into thinking you have not been awake as long because it can't see the adenosine. It fools your brain and body into thinking it isn't time for sleep yet, but it doesn't fool your body into actually needing less sleep. That's the key because caffeine creates this vicious cycle. We need caffeine because we're tired, but then caffeine makes it hard to sleep so we need more caffeine. You will still have to pay the piper at some point. It doesn't actually get rid of adenosine like taking a nap does. It only hides it and only hides it for a while. All right, so when should you stop drinking caffeine? I say to avoid caffeine late. Everyone has a different tolerance to caffeine, similar to their tolerance to alcohol based on how quickly they can break it down. This means that I can't tell you when to stop drinking caffeine, but I can tell you about the typical person. The half life of caffeine is five to six hours and the quarter life is 10 to 12 hours. What this means is that if you have a cup of coffee at noon, half of it will be out of your system in five to six hours. Then three quarters of it will be out of your system 10 to 12 hours. If you have that cup of coffee at noon, it's the same thing as having half a cup of coffee at five or six or a quarter cup of coffee right before trying to fall asleep at 10 or 12. They would have the same impact. The best advice I can give you is don't drink a cup of coffee at noon if you wouldn't drink half a cup of coffee at five or a quarter of a cup of coffee right before bed at 10. You might be thinking, wait a minute, I get caffeine bothers some people. My wife, she's super sensitive to caffeine. She can't have any caffeine after probably two and she knows it. What if you think caffeine doesn't affect you? This was me. I could drink a cup of strong coffee or a 20 ounce Mountain Dew right before bed and still fall asleep. Here's the bad news for you. If you don't think caffeine bothers you, sorry, it does. Even if you aren't very sensitive to caffeine and it doesn't impact your ability to fall asleep and stay asleep, so if you can pop into bed and fall asleep and you don't wake up 10 times in the middle of the night, it is still impacting how much deep sleep you can get. We've talked about deep sleep. Deep sleep is where hormones reset and it's where muscles repair, et cetera. Evening caffeine can decrease the non-REM deep sleep by 20 to 40 percent and you're not aware of it at all. Caffeine is literally destroying your sleep quality whether you know it or not. What's the science say about this? Caffeine effects on sleep take in zero, three, or six hours before going to bed. This is a randomized controlled trial. There is some wiggle room for different people, but this study showed that any caffeine up to six hours before bed seems to cause problems in almost everyone. Consuming caffeine up to six hours before bed significantly worsened sleep quality. The magnitude in reduction of total sleep time suggests that caffeine taken six hours before bed time has important disruptive effects on sleep. The study actually says that. I wish this study would have gone even farther because I think looking at the study, we can definitely say that you should avoid caffeine six hours before bed, but we've already said that caffeine has a quarter life of 10 to 12 hours, so I would recommend pushing your last caffeine back even farther than that, but let's start here. No caffeine six hours before bed based on the science. What's the key takeaway? Caffeine doesn't decrease your need for sleep. It only tricks your brain into thinking that it isn't time for sleep. If caffeine actually destroyed a dentosine, then it would literally make it so you needed less sleep, I guess, but it doesn't do that. It only hides the receptors temporarily, and then caffeine decreases your sleep quality whether it feels like it to you or not. What's our action steps? We have to try a caffeine free experiment, but I don't mean no caffeine at all. There's nothing wrong with caffeine early in the day. If you're a caffeine addict and you don't want to get headaches and you need your fix or whatever, that's fine. I still consume caffeine in the morning. I've just found, so the sweet spot for me is 10 hours. I have no caffeine 10 hours before bed, so you have to determine how late you can drink caffeine before it starts impacting your sleep. Again, I've talked to this before, but I used to be exposed to light all night and caffeine all night and I slept terribly. The two biggest things that I've done is blocking blue light in the evening and no caffeine 10 hours before bed, and those two things alone have transformed me. I'm so much more tired at night. I go to bed so much easier. I sleep so much better. I wake up so much earlier. These are huge, huge deals. Okay, a few more things. Decaffeinated coffee and tea are perfectly fine. Coffee and tea are actually great sources of antioxidants, so the antioxidants in coffee and tea are actually really, really good for you. But I would say bonus points, if you get rid of your caffeinated coffee late in the day, bonus points if you switch to a tea that has sleep-enhancing benefits like chamomile or passion flower. We'll cover those later in the course. Okay, so no caffeine at least six hours before bed. I'd recommend much longer than that and see how much it helps you. Make sure you're writing it in your sleep journal. Okay, I hope this video helped. Have a wonderful day. Be blessed.