Why do you still sleep with six cups of coffee? Coffee is absolutely safe.

You must be wondering why some people drink six cups of coffee a day and fall asleep like a baby an hour later, while others get so excited when they only have a cappuccino after dinner.

To be sure, coffee is absolutely safe. According to the FDA, Americans consume 300mg caffeine every day, and the Mayo Clinic says it is safe for adults to take 400mg every day. Coffee is not only the most widely consumed form of caffeine, but also has a lot of health benefits. Studies have shown that moderate consumption of coffee can help protect against liver disease, provide greatly improved antioxidants, and even protect brain nerves and reduce the risk of Parkinson's disease.

Caffeine is consumed by coffee, tea, soda and chocolate, and although the safe daily intake of caffeine has been clear for years, everyone's excited response to caffeine cannot be summarized in the same way. The body's chemical process of processing caffeine also reacts differently based on several key factors, some of which you have never thought of.

Drink coffee often

This may sound counterintuitive, and people who do not consume caffeine regularly tend to feel the reaction more easily than those who consume it regularly. Studies have shown that long-term intake of caffeine will increase the number of small glycoside receptors, so more caffeine is needed to fill the excess receptors and let caffeine play its due role. If you don't know what glycosides are, click here.)

2. Genetic genes

Many people feel "excited" after consuming caffeine, but it is not directly caused by it. Instead, it binds to small glycoside receptors in the brain, leaving dopamine out of control and keeping the resting body from feeling tired. Since everyone's brain is sensitive to caffeine, this is why some people can sleep as usual after drinking six cups, while others can't sleep after one cup.

III. Antibiotics

According to research from the Mayo Clinic, some antibiotics and asthma drugs can have an effect on caffeine in the body. Antibiotics interfere with caffeine metabolism, making it circulate in the body for longer. For example, asthma medicine itself contains caffeine, which can be felt more strongly when used in combination.

4. Anxiety disorder

If you feel anxiety in your daily life, large amounts of caffeine may reinforce your symptoms. "caffeine is the most widely used mood-altering drug in the world," says Dr Roland Griffiths of Johns Hopkins University School of Medicine. In this case, caffeine can cause insomnia in people with anxiety disorders.

Metabolic enzymes

There is an enzyme in the liver that boosts the body's metabolism, which determines everyone's ability to process caffeine. People with fewer metabolic enzymes need to spend more time clearing caffeine from the body, and the longer caffeine stays, the longer it reacts. In contrast, people who produce more metabolic enzymes often need more caffeine to stay excited.

VI. Y chromosome

There is also gender discrimination in the body's ability to handle caffeine, and women are born to metabolize faster than men. A study from the University of Barcelona showed that when a group of college students consumed the same amount of caffeine at the same time, men reacted more than women ten minutes later.

VII. Contraceptive

However, although women are born with fast metabolism, when women are using oral contraceptive, they may have only the metabolic rate of the previous one. Contraceptive contains ingredients that inhibit caffeine metabolism, according to a study. So, the excitement you feel will last longer.