How long does caffeine last in your system?

Coffee is a daily ritual for many people. Some enjoy the aroma and flavor it brings. Some feel like they cannot function properly without a cup of coffee in the morning. Coffee makes us feel more awake and energetic. But why? The short answer is because of the caffeine in coffee. So we wonder what caffeine does to our body and how long does caffeine last in human system. Or any possible side effects? In this post, I will help you to answer to all these questions and help you to understand more about your cup of Joe. 

What happens to you when you drink a cup of coffee?

Coffee beans naturally have caffeine. Different type of coffee drinks contains a varying amount. When people drink a cup of coffee, the caffeine kicks in as a stimulant. It affects the central nervous system, our heart, and muscles. Most of the time, we feel more alert, awake, and energized. 

It can also increase our concentration level. However, for people who are sensitive to caffeine, they can experience some side effects that will be analyzed in the latter part of this article.  

Where does caffeine come from?

Caffeine is a naturally occurring substance found in coffee beans, tea plants, cocoa beans, and some other plants. The amount of caffeine in coffee depends on many factors, like the type of beans, roasting level, and brewing methods. 

Robusta coffee bean has almost twice as much caffeine compare with an Arabica coffee bean. The roasting level (light, medium, dark) alters the caffeine content of coffee further. And then, to make a cup of coffee, people use different brewing methods. It will also affect the overall caffeine content in coffee.

According to US Department of Agriculture, one 8 fl. oz cup of coffee contains 70 to 140 milligrams of caffeine while the same size cup of French press coffee contains, on average, 101 milligrams. 

How long does it take for coffee to kick in?

Most of us drink coffee, experience the effect, but do not count down to the minutes of how long it takes for caffeine to kick in. That is when studies come in handy. They found out that caffeine starts to have an effect after the 10 minutes mark. But after 45 minutes is when the caffeine concentration in the blood reaches its peak (BBC Studios) 

How long does caffeine stay in our system?

It is quite hard to answer this question. Depend on how much you drink, the intensity of your coffee, the caffeine content will vary. According to the American Academy of Sleep Medicine, caffeine from a cup of coffee generally reduces by half in 3 to 5 hours. It is also the caffeine half-life, meaning the time it takes for the human body to eliminate caffeine by 50%. The rest of it can continue to stay in our body for hours. 

Another similar question that many of us wonder is that: How long does coffee keep you up? That again depends on many factors. It can be the type of coffee you drink, how strong it is, or your body’s sensitiveness to caffeine. Some people have trouble falling asleep hours after their last cup of coffee, while others do not experience much change to their sleeping patterns. 

But like mentioned above, we know that caffeine levels in our body reduced by half every 3 to 5 hours. That can be a good benchmark for us to understand the length of an effect caffeine has on our body. If you drink a cup of coffee in the late afternoon, chances are there is still caffeine circulating in your body. That can be a factor that keeps you up at night. 

What are the side effects of caffeine?

Caffeine has both good attributes and negative attributes. It increases our reaction time, mental performance, and promote alertness. But at the same time, it does have some side effects. 

For people who are caffeine-sensitive or with a high dose of caffeine, they can experience coffee jitters. It includes sweating, nausea, muscle tremors, increase heart rate, or stomach discomfort. It can also reduce the quantity as well as the quality of sleep. Withdrawal symptoms from caffeine include headache, insomnia, or tiredness. 

It is best in these cases to consult a doctor to know if you can continue to drink coffee or other drink that has caffeine. You may need to cut back or avoid it to prevent coffee jitters and for a healthier body and mind.  

Other products that contain caffeine besides coffee

Besides coffee, tea is another popular drink that has caffeine content. People all around the world drink tea, in some countries even more often than coffee. The amount of caffeine in brewed or steeped tea is considered lesser than in brewed coffee. 

One 8 fl. oz (237 ml) cup of brewed green tea contains 25 to 29 milligrams of caffeine. Brewed black tea can carry a bit more at 25 to 48 milligrams per cup. While on average, a cup of coffee contains 95 milligrams.

Other products that contain caffeine are cocoa beans, Brazilian plant Guarana, or the South American plant Yerba Maté. Manufacturers also add caffeine to some soft drinks, energy drinks, or medicine.