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Caffeine is the most widely used stimulant in the world. For many of us, a cup of coffee or tea is almost as routine as breathing. It helps us wake up in the morning, beat the afternoon slump, and allows us to pull all-nighters necessary to meet deadlines. 

Given how commonplace it is, it's easy to forget that caffeine is a psychoactive substance. We all know that alcohol and cigarettes are unhealthy habits, but does caffeine deserve the pass we give it? Excessive intake can lead to anxiety and sleep disturbances, while very high doses can lead to serious health problems like seizures and heart issues, but what is it doing to the body when taken within "safe limits" every day?

What is caffeine?

Caffeine is a naturally occurring stimulant found in leaves, seeds, and fruits of more than 60 types of plants, including coffee beans, tea leaves, and cacao pods. It belongs to a class of chemical compounds called alkaloids and acts as a central nervous system stimulant, blocking the sleep-promoting neurotransmitter adenosine, resulting in alertness, concentration, and wakefulness. 

It's also sometimes added to medications, sodas, and energy drinks to enhance their stimulating effects. 

What are the risks?

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The same mechanism that makes caffeine so appealing is also what makes it dangerous. According to the US Food and Drug Administration, up to 400 milligrams of caffeine a day (roughly four to five cups) is considered safe for most healthy adults, but this varies from person to person. 

Genetics, age, biology, and lifestyle factors can all affect how the body processes it. People who metabolize it more slowly can feel jittery, anxious, or wired for hours from a single cup of coffee. Similarly, people with lower body weight often experience the effects more strongly. If you're a smoker, the speed at which you metabolize caffeine will be quicker, and hormonal factors can slow it down. What feels like a normal habit for one person could be a stressor or stimulant overload for another.

When consumed above recommended levels, caffeine can lead to a range of negative health effects, ranging from uncomfortable to very dangerous. It can trigger symptoms like rapid or irregular heartbeat, elevated blood pressure, anxiety, restlessness, nausea, vomiting, tremors, and insomnia. 

At very high intake, serious toxicity can occur, causing seizures, respiratory distress, and in extreme cases, death. This happens because, when taken at high levels, caffeine is metabolized more slowly, and the body can be overwhelmed. Toxic levels have been seen at doses of around 1,200 milligrams. 

That being said, coffee and tea drinkers can relax for the most part, as these toxic quantities would be hard to reach with these types of beverages. You would essentially need to take caffeine in its powder form or overdo it on energy drinks to experience these serious symptoms. 

The impacts of caffeine aren't all bad. In fact, when consumed in moderate amounts, it's been associated with several potential health benefits, like improved cognition, boosted metabolism, and lowered risk of Parkinson’s disease. 

But even so, no matter how you slice it, caffeine is a substance that alters our brain chemistry. Why we're all so relaxed about it comes down to social acceptance, the fact that it's legal, and that it's deeply ingrained in work culture. For most people, there's no reason to cut it out of their life entirely, but understanding its potency and how it affects people differently can help you enjoy its benefits without paying the hidden costs of disrupted sleep, anxiety, or stress.