One of the popular chilled coffee drinks with milk typically has 80mg of caffeine – and the makers caution consumers to drink it in moderation. Energy drinks such as Red Bull

“Children’s and young adults’ average caffeine consumption has increased by more than 70 per cent over the past 30 years, and an end to this rise is not in sight: the drinks industry is posting its fastest-growing sales in the segment of caffeine-laden energy drinks. Not everybody is pleased about this development. Some people are worried about possible health risks caused in young consumers by the pick-me-up …
The conclusions call for caution: in pubescent rodents, caffeine intake equating to three to four cups of coffee per day in humans results in reduced deep sleep and a delayed brain development.
Both in humans and in rats, the duration and intensity of deep sleep as well as the number of synapses or connections in the brain increase during childhood, reaching their highest level during puberty and dropping again in adult age. ‘The brain of children is extremely plastic due to the many connections,’ says [lead author] Huber. When the brain then begins to mature during puberty, a large number of these connections are lost.’”

Energy drinks and sports – but not for children, research is showing

“Coincident with this rise in caffeine use is the development of novel, caffeine-containing beverages called energy drinks.
These drinks contain caffeine levels ranging from 50 mg (equivalent to a can of soda) to 500 mg (equivalent to five cups of coffee) and, often, very high levels of sugar (Energyfiend website, 2008). Energy drink sales have grown by more than 50% since 2005 and represent the fastest growing segment of the beverage industry (Chandrasekaran, 2006).
Energy drinks are marketed specifically to young adults and children with advertisements featuring high risk activities and extreme sports, such as rock climbing, parasailing, and BASE jumping and with catchy slogans such as “Red Bull gives you wings” and “Excite your sense” (reviewed in Miller, 2008a). This, coupled with growing concerns from parents and physicians, strengthens the imperative to empirically determine the effects of caffeine use in children.”

“Caffeine is the most widely consumed stimulant. It is known that caffeine consumption, in particular among adolescents, has increased significantly in recent years …
No matter what mechanism applies our study shows that caffeine interferes with cortical maturation during a critical developmental period. This might also be of clinical importance since the critical period of synapse elimination during adolescence is associated with an increasing incidence of psychiatric and mood disorders, such as schizophrenia, anxiety, substance abuse and personality disorders [67]. Thus, it will be important for future studies to investigate the effects of chronic caffeine application during critical periods of development in animal models for psychiatric and mood disorders.”