Caffeine affects the body by acting as a stimulant on the central nervous system. It blocks the action of adenosine, a neurotransmitter that promotes sleep and relaxation. This causes an increase in the activity of other neurotransmitters such as dopamine and norepinephrine, leading to increased alertness and decreased fatigue. Caffeine can also cause an increase in heart rate and blood pressure, and can lead to insomnia if consumed in large quantities or close to bedtime. It can also cause increased urine output and can act as a diuretic. Some people may also experience jitteriness, anxiety, or upset stomach as side effects of caffeine consumption.

How much caffeine is okay each day?

The recommended daily intake of caffeine varies depending on the source you consult. However, most health organizations agree that moderate caffeine intake is safe for most adults. The FDA suggests that up to 400mg of caffeine per day, which is roughly the amount in four cups of brewed coffee or 10 cans of soda, is not generally associated with negative effects. However, it's important to note that individual tolerance and sensitivity to caffeine can vary greatly and some people may be more susceptible to the negative effects of caffeine. It's also important to consider that caffeine can be found in many sources like tea, chocolate, and energy drinks, so it's important to be aware of your total caffeine intake from all sources. It's always a good idea to consult with your healthcare provider if you have any concerns about caffeine intake.