What is a common effect of caffeine on the body?

Caffeine is primarily known for its stimulant properties, which contribute to enhanced alertness. When consumed, caffeine blocks the action of adenosine, a neurotransmitter that promotes sleep and relaxation. This action leads to increased neuronal activity in the brain and the release of other neurotransmitters, such as dopamine and norepinephrine, which improve mood, energy levels, and focus. Consequently, many individuals consume caffeine to help them stay awake and attentive, particularly during tasks that require concentration or when they are feeling fatigued.

The other options do not accurately capture the most common effects of caffeine. For example, improved sleep quality is generally not associated with caffeine, as its stimulating effects can lead to increased wakefulness and difficulty in falling or staying asleep. Similarly, increased hydration is not a typical effect since caffeine can have mild diuretic properties, potentially leading to increased urine output. Lastly, while some people may experience decreased anxiety after caffeine consumption due to heightened alertness, it can often trigger increased anxiety or jitteriness in others, particularly in high doses.