How caffeine affects your sleep
Issue #80: How caffeine affects your sleep Read Time: 8 minutes Good morning, 66.1ers. Housekeeping: We had planned to launch the paid version of 66.1 this week. You can expect that launch in early January. A quick favor: If you find today’s newsletter valuable, could you please share it with one person you think might find it useful? This would make all the difference to us as we build this newsletter and help people live healthier, for longer. A quick refresher for anyone who's new to the newsletter: 66.1 is the average health span (years lived without a serious disease) in the US. We're here to extend that. In case you missed it: In this week's issue of 66.1: A deep dive into how caffeine affects your sleep. -The effects of caffeine on sleep duration and quality I touched on the health effects of caffeine back in October, but I've had a number of reader questions about it since then so we're going to go deeper on the topic today. BackgroundYou’ve probably heard the whisperings. Caffeine raises your blood pressure. It makes you anxious. It disrupts your sleep. Activates your digestive system. It’s an antioxidant. It reduces your sperm count. You shouldn’t drink it while you’re pregnant. Good, bad, and otherwise, the list of wives’ tales and urban legends surrounding caffeine is long. A daily coffee drinker myself and well aware that many of you consume caffeine on a daily basis (as do 85% of Americans), I dove deep to make sense of this turbocharged beverage. I set out to make sense of the effect of caffeine on your health writ large, but as I continued to read, I realized that I’ll need more than one issue to address all the ways caffeine affects your health. So, this week, we’ll focus on how caffeine affects your sleep, a critical component for long-lasting health. In future issues, we’ll focus on other effects of caffeine on your health. The world's most-used psychoactive substanceCaffeine can be a lot of fun: it helps you think fast, talk faster, and generally be more productive. That buzzing feeling you get when you're halfway through your first cup of coffee in the morning is no coincidence. That's caffeine activating your brain. There's a reason people like to "get coffee" when they are meeting someone--the extra jolt from the caffeine stimulates conversation and idea generation. Author Michael Pollan goes so far as to say that the coffee break, which was created in the U.S. in the 1940s as a way to increase worker output, is "the best evidence of caffeine's gift to capitalism." Yes, there are many great reasons to enjoy your caffeine. But you've also probably run into a few challenges in your days as a caffeine drinker, especially related to your sleep. For example, maybe you've had a 4PM cup of coffee, resulting in you lying in bed tossing and turning until the early morning hours. How can a substance that has so many positive effects also have such frustrating side effects? Let's dive in. What the science saysNot a sleep replacement If caffeine was a sleep replacement, you could, in theory, drink coffee instead of sleeping. But we know that doesn’t work. Caffeine might get you through one all-nighter, but you’re not worth a darn the next day. A study by Gardiner and colleagues found that using coffee to compensate for a poor night of sleep is likely to damage your next night of sleep. According to their study, caffeine consumption (especially later in the day) reduced total sleep time by 45 minutes and reduced sleep efficiency by 7%. To optimize your sleep quality, the authors’ suggestion is to consume your coffee at least 8.8 hours prior to bedtime. That sounds like quite a long time, but there’s sound rationale behind this suggestion. Timing is everything The suggestion to stop drinking coffee 8.8 hours before bedtime comes from a fascinating bit of biochemistry: the half-life (amount of time it takes your body to clear half the caffeine you consume) of caffeine can range from 1.5 to 9.5 hours, depending on the individual. Put another way, it will take between 3-19 hours to clear all the caffeine from your system once you stop consuming it. If you want to optimize your sleep quality, it’ll be important to give your body time to clear the caffeine from your system before going to bed. Assuming your physiology falls somewhere in the middle of this range, it’s going to take your body 10-12 hours to clear the caffeine from your system. Working backward from a 10 PM bedtime, for example, you’ll want to stop drinking caffeine by 10 AM to give your body 12 hours to clear the caffeine from your system. With this bit of science in your back pocket, it’s hardly surprising that Gardiner suggests at least 8.8 hours between coffee and bed. In the figure below, cut-off times to minimize sleep disruption are established for black tea, coffee, and a pre-workout supplement. Note that the larger the dose of caffeine, the earlier the advised cut-off time. You can view the full-sized image here. If you are giving your body 8.8 hours to clear the caffeine from your system and still experiencing restless sleep, I encourage you to experiment with moving your cutoff time earlier in the day. If you’re on the extreme end of the spectrum and your body requires 19 hours to clear caffeine from your system, it’s quite possible that you and caffeine may not be right for each other. Watch out for the roller coaster There are a lot of folks who find themselves riding the following caffeine-alcohol roller coaster: 3+ cups of coffee to jump start their day, including drinking coffee through the afternoon hours. At 5 PM, still wired, they head home from the office. Needing to wind down from a stressful work day, they have a glass of wine. It’s a logical approach to energy management–get energized for your workday by consuming a stimulant early in the day and relax with a depressant later in the day–but it’s a dangerous one for a few reasons. First is mentioned above: caffeine doesn’t leave your system for 10-12 hours on average after consumption. You'll still have caffeine coursing through your veins at 10 PM if you’re consuming it late in the afternoon. Second is the deleterious effect of alcohol on sleep. Unfortunately, alcohol can be deceptive. Because it’s a depressant, “alcohol is initially sedating, (but) this effect disappears after a few hours, resulting in a fragmented and disturbed sleep in the second half of the night” (Colrain et al). In other words, you might fall asleep quickly thanks to a glass of wine, but you’re likely to have a shoddy night of sleep after that. Now you’re stuck in a dangerous cycle: because you didn’t sleep well, you throw back an extra cup of coffee at work tomorrow. Wired and anxious when you get home, you turn to an alcoholic beverage and the cycle continues. Not to worry, though. There are a few rules to help navigate your caffeine consumption so it doesn’t interfere with your sleep. Applying it to your lifeI see 3 ways you can apply these scientific findings to your life, starting today: 1. Stop at 2 cups This practice helps in 2 different ways. First, cutting yourself off at 2 cups of coffee (or the equivalent--roughly 200 mg caffeine) makes it much easier to stop drinking caffeine at least 8.8 hours before you go to bed, helping you wind down and keep your sleep quality high. Second, it reduces the likelihood that you’ll be reliant on alcohol to unwind after a stressful day at work, risking further damage to your sleep quality. And that improved sleep quality will reduce the likelihood that you’ll be reaching for yet another cup of coffee to compensate for feeling groggy tomorrow. An upward spiral. 2. Give yourself a cutoff time If you’re the type who enjoys an afternoon cup of coffee, it might be wise to implement a hard cutoff time on your caffeine consumption. If you currently consume coffee until 3 PM, try moving that cutoff by just an hour to start. Go for 2 PM this week. If that works well, try 1 PM next week. You get the idea. Tackle small changes to get started and build momentum, resulting in a significant change over time. 3. Reverse your psychology We tend to consume more caffeine when what we actually need is to cut ourselves off early so we can get a good night’s sleep. We see it is a way to "make up" for poor sleep. Rather than using caffeine to compensate for poor sleep, consider taking the opposite approach: on days following a good night’s sleep, allow yourself an extra cup of coffee. On days following a poor night's sleep, take that as a sign that you need to go easy on the coffee today so you can sleep well tonight. All told, it seems caffeine and sleep can coexist, so long as you consume caffeine in moderation and early in the day. See you on Wednesday. Have fun out there. Marcus Why 66.1? |