Plenty of kids suck down energy drinks, Starbucks and sodas (The American Academy of Pediatrics (AAP) says 73 percent of kids consume caffeine on any given day) but you may want to encourage your kids to cut back. A study in the journal Pediatrics shows exactly how caffeine affects kids' blood pressure and heart rates — especially in teens — meanwhile, the AAP says caffeine should not be consumed by kids at all). In a test study of 95 children of various ages, researchers found that caffeine affected boys and girls in the same way at ages 8–10. But puberty in kids reveals another story when caffeine comes in to play: Teen boys are more likely than girls to experience decreased blood pressure and increased heart rate when they ingest caffeine. Caffeine also decreases a teenage girl's heart rate during the last phase of her menstrual cycle and increases blood pressure during the first phase of the menstrual cycle. While the U.S. Food and Drug Administration doesn't offer a standard on how much caffeine is or is not safe for children, it IS known that caffeine is a drug that can cause overstimulation, increased blood pressure, increased heart rate, anxiety, possible insomnia, and according to the pediatric neurologists at Vanderbilt, headaches.