Just because few tweens get their morning kickstarted with a cup of Mom and Dad's coffee, doesn't mean they aren't loading up on the caffeine in other ways throughout the day. The popularity of highly caffeinated energy drinks, sugar-laden coffee-based treats like Starbucks' frappucino line and the old standby sodas means that many tweens are consuming caffeine regularly.
The general consensus among doctors is that tweens and teens should consume fewer than 100mg of caffeine per day, with many more urging no more than 80mg per day. For perspective, a can of soda has about 50mg of caffeine. A frappucino ranges from 10-195mg depending on the size and style. Energy drinks vary widely, but common brands have between 80-180mg per can. If you know your tween consumes these beverages even sparingly, check out this database with her and find the caffeine content of her preferred drinks. Then work with her to limit her caffeine intake and talk about the potential for sleep disruption, dehydration and even mood disturbances like anxiety. Check out these helpful websites here and here for more information on the effects of caffeine on your tween.