Whether you get your daily caffeine fix from coffee, tea, or a canned energy drink doesn't make much of a difference. It's still a stimulant with some positive and negative effects.
For starters, caffeine makes most of us feel more alert and awake. But while it can keep us focused, too much can also backfire. And it also affects everything in our bodies from our digestion to our metabolism and vision.
It’s natural to grow increasingly tired throughout the day — our brains naturally produce more and more of a molecule called adenosine from the time we wake up until the time we go to sleep. Scientists think this helps us get to bed at night.