How Long Can Caffeine Keep You Awake

It's 3 pm, and you're half asleep. Was that cup of coffee that you had in the morning not enough? Coffee keeps you awake for a few hours, but many more factors can change that. Let's look into that.

How Does Caffeine Keep You Awake?

To know how caffeine keeps you awake, we should first look into why we get sleepy in the first place. Every animal's (including yours) body evolved to move around during the day, catching prey or finding any other type of food. That means that your ancestors' bodies were put under much physical and mental pressure. Just like anything, when you spend energy, you need to recharge. One of the ways to do that is through food, which only helps your body recover, though. Sleep is how your mind recovers. 

Your body tells you you're getting tired by aches, pains, and even weakness. While there are no pain receptors in the brain, your mind also becomes sluggish. As a result, you'll feel like you're not that creative and can't concentrate that easily anymore. A few hours later, you'll start feeling you need some sleep. What's making you sleepy is a compound your brain produces called adenosine.

Adenosine is vital in many biochemical processes and is an important neurotransmitter. However, it's a byproduct that your brain releases when you concentrate for extended periods and hinders arousal, making it hard to think, move fast, and eventually make the right decisions.

The natural way to block it is by getting some sleep. When you're asleep, your body's muscles relax, and your brain has some time to stop concentrating and process what's happened during the day.

What caffeine does is stop the binding of adenosine with adenosine receptors. It does that by binding to adenosine receptors but not setting them off. As a result, it prevents you from feeling tired. 

After drinking coffee, to make it easier to understand, there's something of a battle between a superhero and a villain in your body. While adenosine can be seen as the villain, making the city (your body) miserable and unable to get rid of him, caffeine comes to the rescue. It first stops adenosine from making you more tired and then energizes you. But, unfortunately, on the way to energizing you, it causes havoc. The city is partly destroyed like in any superhero movie, but the superhero beats the villain.

Besides giving you energy, caffeine can have a lot of side effects. These can include anxiety, insomnia, and even diarrhea. While that's not what most people experience, more than one cup of coffee in the morning and one in the afternoon can be too much.

When Does Caffeine Kick In?

When caffeine kicks in depends on a few factors. The most important of them is how your body reacts to it. If you are very sensitive to caffeine, you will feel the effects faster than most people, but usually, it takes around 15 to 45 minutes. 

Other factors that affect how fast you will feel the kick from your cup of coffee are the coffee, the beans, and the brewing method used. Also, if there's more caffeine in the coffee you chose, you will start feeling the effects sooner, and they will be stronger. 

How Long Does Caffeine Last?

It takes caffeine a long time to altogether leave your body. Depending on how used you are to having caffeine in your body, it can take up to 12 hours to be completely absorbed. Therefore, if you drink a coffee when your day starts at 8-9 am, there will still be some caffeine in your system by 8-9 pm.

According to the Food and Drug Administration, the half-life of caffeine is four to six hours. So that's how long it takes for half of the caffeine in your drink to be absorbed.

A four-ounce cup of drip coffee, which you probably drink at home, contains around 100 mg of caffeine. So, if you have one in the morning, when you get to the office, you will still have around half of that at 3-4 pm, when most people have their second cup of coffee for the day. So, if you are like most people, you will still have around 50-60 mg of caffeine in your body by the time you plan to sleep. Whether it's going to prevent you from sleeping depends on a few more factors.

How Does Caffeine Affect Sleep?

The main effects of caffeine are to make you less sleepy and also make it harder to fall asleep. Even if you have no problem falling asleep, coffee can make you wake up a lot during the night. You might not feel it or remember it, but that prevents you from resting. 

Caffeine may interrupt your sleep because it makes your brain more easily aroused. It makes it more sensitive to external stimuli, such as sound, light, or movement and makes it harder to ignore them. 

One of the hormones produced when you're under stress is cortisol, and another is adrenaline. This increased sensitivity to external factors stresses your brain and body, releasing more of these hormones. 

While evolutionary, they were beneficial and helped your ancestors survive by making them more alert, and it's improbable that you need to be alert when in your bedroom. However, for the 21st century, you might want to cut on drinks with a high level of caffeine.

Can Caffeine Cause Insomnia?

In some cases, caffeine can cause insomnia. If you're sensitive to it or have been more stressed out lately, a single cup of coffee can make it impossible to fall asleep. However, many other things can keep you awake at night, so you can try lowering their influence if you find it hard to sleep.

What to Do if You Can't Sleep?

If you find yourself lying in bed, unable to sleep, there are a few things that can lower the effect of caffeine on your body. 

A good starting point is to drink more water. It helps your body process anything, including caffeine. If you drink enough of it during the day, you're more likely to have gone through all the caffeine in your system before you go to bed.

Another approach that you can try is to try to lower your intake of other drinks and foods that contain higher levels of caffeine. These can be energy drinks and anything with cocoa.

The best way to fall asleep more quickly is to limit blue light as much as possible. Our minds are used to waking up with blue light as that's the predominant color just before the sun rises. It's a natural reaction that meant it was time for the day to begin. Nowadays, though, we have a lot more sources of blue light, which can mess with your brain. These can be LED lights and any sort of screen. So if you still want to use your smartphone or laptop, you should turn on Night mode which filters out most of the blue light.

Then, you also have all the tips that you've heard before: to eat at least a few hours before bed. We also recommend not doing sports before bed and not reading anything too stimulating.

Why Does Coffee Affect Everyone Differently?

We all have a friend drinking a coffee just before bed and sleeping like a baby, but why is that?

Just like anything, caffeine affects most people differently. There's a genetic factor to it, but it's not entirely figured out by medicine yet. What has been figured out, though, is that the enzyme that helps metabolize caffeine, the cytochrome P450, is produced in different amounts and with different intensities.

A few more lifestyle factors can affect how much caffeine affects you. The main one of these is your tolerance to caffeine.

Some people are born with a higher caffeine tolerance, but generally, the more caffeine you're used to drinking, the less sensitive you will be to it. So, for example, if you've been drinking coffee since you were 15, and have been gradually increasing your intake, the same amount of caffeine will be affecting you less and less.

Another factor that you should consider is your age. For example, a 1998 study that you can find in the National Library of Medicine concluded that people aged 65 to 70 need around 33% more time to metabolize caffeine.

What Other Effects Does Caffeine Have?

Caffeine affects your body in a variety of ways. So on top of the already mentioned anxiety and higher alertness, there are a few more things you should consider. We've split them into positive and negative effects, so it's easier for you to process.

Positive Effects of Caffeine

  • Reduced risk of a stroke. Research conducted among 360 000 people concluded that those who regularly drink coffee have a 32% lower risk of a stroke. The improved cognitive ability of caffeine intake and the antioxidants in coffee are behind that. 
  • Lower risk of type 2 diabetes. A recent study showed that after looking at data from 100 000 people, those who drink coffee regularly have a 17% lower risk of type 2 diabetes.
  • Improved Memory. A 2014 study concluded that coffee causes your memory to improve due to the high alertness it creates. 

Negative Effects of Caffeine

  • Higher blood pressure. A study found out that a continuous high intake of coffee can cause higher blood pressure. If you have a history of HBP in your family, you should consult a doctor about your caffeine intake.
  • Higher risk of anxiety. As we already mentioned, caffeine can make you more anxious because it stimulates the production of cortisol and adrenaline. So if you're feeling uneasy when drinking coffee, you should consider decaf or cutting it out of your diet altogether. 
  • Stomach issues

How Much Coffee Is Too Much?

A healthy amount of caffeine depends on the same factors we talked about earlier: your sensitivity to the compound, genetics, diet, and lifestyle. Generally, we recommend you don't drink more than two cups of coffee per day. If you feel any discomfort after drinking coffee, you should consider seeing a doctor.

What Is Caffeine Withdrawal?

If you drink coffee regularly, you might develop a dependence on it. If you find it hard to wake up in the morning without caffeine fully, you might have gotten hooked on it. It's not a reason to worry, as it has its benefits, and while it's addictive, it's easy to control your intake.

If you cut coffee out of your diet, you will go through caffeine withdrawal. Some symptoms of that can be sweats, chills, and pounding headaches if you don't drink caffeine. However, you can get over it by not taking any caffeine for a few days. 

Final Thoughts

Coffee is the second most widely consumed drink globally, only after water, and one of the main reasons for that is its high level of caffeine. But, depending on your caffeine tolerance, a cup of coffee can keep you awake anywhere from 4-5 to 12 hours.  

And if just one coffee in the morning is not enough for you, you probably need a Moka pot. They are easy to use and make strong, delicious coffee in just a few minutes. So get your high-quality stainless steel Moka pot from our store now!