Is drinking coffee a health-boosting or healthy thing? Let’s start with how coffee keeps us awake

Coffee has a refreshing effect on many people, but some people say that drinking coffee is an over-consumption and overdrawing the body is harmful to health. Is this true? Let's first understand how coffee can make people not sleepy, and then how to drink coffee reliably.

Coffee can have such a miraculous effect because of caffeine , which is a natural insecticide in some plants . Plants cannot run away when they encounter danger, so they have selected some defense mechanisms in the process of evolution. Purine alkaloids to which caffeine belongs are one of them. It can paralyze the nerves of insects, thus avoiding being eaten. If it encounters some greedy ones, it can also poison them to death.

However, don't be afraid. Although there are individual differences, it is generally believed that if caffeine is to be fatal orally, you need to take 10 grams of pure caffeine. If you want to achieve this through drinking coffee, water will burst you. Therefore, it is deceptive to talk about toxicity without considering the dosage, and the current mainstream scientific community believes that drinking coffee in moderation every day is beneficial. Note that there are benefits rather than risks.

Of course you have to drink in moderation. The safety standard given by the US Food and Drug Administration (FDA) is no more than 400 mg per day , which is about two large cups of American coffee. Drinking too much may really cause dependence, and addiction is not fun.

(Daily safe intake of caffeine established by different organizations)

Speaking of addiction, let's first explain the principle of how caffeine makes people not sleepy. Simply put, its method of refreshing is a different way, not through stimulation, but "blocking". We feel sleepy and tired, which is inseparable from a substance called adenosine , which is an inhibitory neurotransmitter that promotes sleep .

When our physical strength and energy are almost exhausted, adenosine will bind to adenosine receptors, and some hormones such as adrenaline will slow down their secretion, and brain activity will decrease, causing fatigue and sleepiness. Coincidentally, the structure of caffeine is very similar to that of adenosine. If you have drunk coffee at this time, caffeine will take advantage of the situation and quietly join hands with adenosine receptors, occupying the place of adenosine and blocking the binding of adenosine and adenosine receptors. It's a bit like I blocked the keyhole. Although I can't open the door, your original key is also useless. In this way, the brain cannot receive the signal that the body is tired and needs to rest, various hormones continue to be secreted, neurons continue to be active, and naturally you can continue to be high.

Of course, some people say that drinking coffee doesn't work. Indeed, there are genetic differences between people. And it is also closely related to the time you choose to drink coffee . If you want coffee to work best, you probably have to drink it a little earlier. This is easy to understand. When you are particularly sleepy, adenosine and adenosine receptors have already been connected, and caffeine has nowhere to go, so it naturally has no effect.

But you don’t need to drink it too early. The average half-life of caffeine metabolism in the human body is 5 hours . That is to say, after 5 hours, half of the caffeine has not been metabolized. So if you know when you are most likely to feel sleepy, you can drink it 3 or 4 hours in advance.

Although coffee can refresh the mind , it is not a panacea . A research team once evaluated and found that caffeine can only partially relieve the drowsiness caused by lack of sleep, but it will still affect high-level tasks, such as surgery and driving. Therefore, the most important thing is to rest well and get enough sleep.

Let's go back to the adenosine receptors. When caffeine occupies the receptor position, adenosine does not leave. They are still around the neurons. Once the caffeine is metabolized, it will be quickly replenished. At this time, people will feel sleepier and more tired. This is also called " caffeine crash ". You can't recover if you don't sleep at this time.

Finally, we are talking about caffeine here. When it comes to drinking coffee, if you like to add sugar, milk, nuts and snacks, then you should pay more attention to the calories!