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    Better sleep

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    How Caffeine Impacts the Body


    Caffeine affects everyone differently. It can give you a nice little boost, but there are downsides too. In order to understand if the benefits outweigh the disadvantages, you'll want to understand just how caffeine impacts your body.

    Caffeine is a Stimulant and Energy Booster


    Caffeine is essentially a fast-acting stimulant that boosts energy and improves your mood. It can start affecting you within 15 minutes of consumption.


    More specifically, it acts as a receptor-antagonist for adenosine, a signaling molecule that stimulates the part of the brain that controls attention and concentration. When adenosine binds to certain receptors in your brain, it slows down neural activity and makes you feel sleepy. Caffeine binds to the same receptors but without slowing neural activity — thus giving you a boost. It also can cause the pituitary gland to secrete hormones that increase in adrenaline, giving you more energy.

    The Effects Vary from Person to Person


    Exactly how caffeine interacts with your body can vary from person to person. An individual's reaction may depend on tolerance levels, genetics, medication, metabolism, anxiety, age, or gender. Some people metabolize caffeine faster than others. Others' adenosine receptors may simply take to caffeine better. If you have anxiety, you may be more prone to feeling jittery from caffeine. Interestingly, men may feel the effects of caffeine more strongly than women.


    Some medications might make you more sensitive to caffeine. Asthma medicine, for example, may already have stimulant-like effects that are enhanced by caffeine. Some antibiotics and birth control pills might cause caffeine to stay in the body longer. Other medications, like headache tablets, may already have caffeine.

    How Much Is Safe?


    It's typically safe to consume up to 400 mg of caffeine a day (which is about four cups of coffee.) But it varies from person to person. If your tolerance is lower, you might want to consume less caffeine than average.


    The half-life of caffeine is usually five or six hours. This means it can take up to six hours for just half of the caffeine you consumed to be eliminated from your body. So don't drink caffeine too late or it might keep you wired at night.


    It's also possible to consume too much caffeine too fast. Taking 1,200 mg of caffeine very quickly might make your heart race, so be careful with too many energy drinks. A concentrated dose of pure caffeine might cause seizures. The FDA warns against pure caffeine, which may be in the form of dietary supplements. Just one teaspoon of pure caffeine might equal 28 cups of coffee at once, which can be toxic.

    Caffeine's Negative Effects


    Caffeine can have negative effects on your body. These can include insomnia, anxiety, irritability, depression, feeling jittery, a fast heart rate or elevated blood pressure, nausea, headaches, or an upset stomach. If you're feeling these symptoms, consider cutting back on the caffeine.


    You can also become dependent on caffeine. This means that when you try to decrease it or cut it out completely, you might have some withdrawal symptoms like headaches, fatigue, or muscle pain. Reduce your intake slowly to avoid this.

    Watch Your Caffeine Intake from Food and Drinks


    If you're trying to cut back on caffeine, watch the labels on your food and drinks. A can of soda might have 30 to 40 mg of caffeine, while a smaller cup of tea might have 30 to 50 mg, and a cup of coffee could have 80 to 100 mg. Caffeinated energy drinks and certain brands of soda have even more.


    Caffeine can be found in unexpected places too. Decaffeinated coffee or tea might still have up to 12 milligrams of caffeine. Chocolate naturally has caffeine, including hot chocolate, candy, or even ice cream or cereal flavored with chocolate. Some plants used as flavorings (like guarana or yerba mate) also have caffeine.


    In summary, while caffeine is safe in moderate amounts, you'll want to watch for signs that you're extra sensitive to it or that you're building a tolerance. While it can be a nice pick-me-up, you don't want to become dependent on it.

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    This information is not intended to replace the advice of a trained medical doctor and is provided to you on a general information basis only and not as a substitute for personalized medical advice. Philips disclaims any liability for the decisions you make based on this information.

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