This is Why Coffee Can Make You Sleepy

There’s a good chance that, like us at The Manual, you adore coffee. We’ll drink a pour-over, an espresso, or a Turkish coffee; we’re not picky. Having said that, despite daily caffeine consumption, the majority of us have experienced feelings of exhaustion or fatigue, particularly in the afternoon. What is going on? To that end, we’re going to examine a variety of articles and studies to determine why coffee makes us sleepy. After discussing why our favourite morning brew may cause us to feel groggy, we’ll discuss a few strategies for combating this sensation and improving our overall health.

If you’re not already aware of how critical sleep is for the brain, listen to this Fresh Air interview with Matthew Walker.

To begin comprehending how coffee affects our brain and sleepiness, it’s helpful to consider why and how we sleep. We began by consulting the New York Times for an answer to the coffee-sleep conundrum. What I’ve learned is that you should view sleep as a gradual tipping point. The process begins as soon as you awaken. Throughout the day, the brain accumulates a chemical called adenosine. As it progresses, you become more exhausted. By bedtime, sufficient amounts of this chemical have been accumulated to enable you to fall and stay asleep. This increasing level of adenosine is referred to as “sleep pressure.”

How Coffee (and Caffeine) Cause Sleep Disruption
Caffeine prevents adenosine from binding to brain receptors when we consume it. This means you will not feel tired. That sounds fantastic. Feel less exhausted, have more energy, and accomplish more. Right? The issue is that your brain should be exhausted and ready to sleep at the end of the day. Rather than that, the mid-afternoon espresso shot reset the clock, and your brain believes you’ve been awake for only six or seven hours. This ultimately makes it more difficult to fall asleep in the evening, resulting in fewer hours of sleep and increased fatigue the following day.

Another result from this is that you don’t feel yourself growing tired until the caffeine wears off. Caffeine has a half-life of five hours. This means that the amount of caffeine in your system is halved every five hours. The cup of coffee you have at six in the morning has halved by 11 a.m., and again by 4 p.m. We begin to feel the sleep pressure that has been building throughout the day as the caffeine wears off. All of a sudden, say mid-afternoon, we feel tired. We collide. And this crash is what sends us to the barista to get a little pick-me-up.

The author of the NYT article, Wudan Yan, explains that when we are not sleeping well (and therefore consume more caffeine) it creates a perfect storm for feeling tired. We consume caffeine, which negatively impacts our sleep, which makes us more tired, which makes us consume more caffeine. It’s a vicious cycle. So how much coffee should we drink? Healthline suggests 400 mg per day as a general rule. This equals about 2-4 cups of 8 oz. coffee per day, depending on how strong your brew it.

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