A teen who drinks coffee isn’t something out of the ordinary. But for the developing mind, caffeine might have its drawbacks, researchers are saying, after finding that consuming caffeine may have inhibited the maturing process of rats' brains.

Young rats that were given caffeine equal to three to four cups of coffee a day — which is even too much for adults — tended to get less sleep, and because of that, their maturing brains suffered, the study found.

“The brain of children is extremely plastic due to the many connections,” Reto Huber, of the University of Zurich, Switzerland, and lead author of the study, said in a statement. Due to a process called synaptic pruning, these connections eventually become lost or consolidated during puberty. “This optimization presumably occurs during deep sleep. Key synapses extend, others are reduced; this makes the network more efficient and the brain more powerful.”

When Huber and his team gave a group of 30-day-old rats caffeine over the course of five days. By monitoring their brain waves — a slow-moving wave meant deep sleep — the researchers were able to see if the caffeine affected their sleeping patterns.

They found that caffeinated rats slept deeply for shorter periods of time, when compared to those that only drank water, and that the effect of the caffeine persisted up to seven days after they stopped drinking caffeine. The caffeinated rats also had significantly more neural connections, indicating that their brains hadn’t matured as much. Because of this, their behavior was affected as well. The rats given caffeine remained timid and cautious, while those given water became curious — a natural sign of a maturing rat.

Although there are obvious differences between a rat and a human’s brain, the researchers said that neural development is still similar, and that more research should be done.

The National Sleep Foundation recommends that teenagers get at least nine hours of sleep every night. Not doing so — about 15 percent get the recommended amount — can limit a teen’s ability to concentrate, learn, remember things, as well as make them irritable or prone to eating unhealthily.

Source: Olini N, Kurth S, Huber R. The Effects of Caffeine on Sleep and Maturational Markers in the Rat. PLOS One. 2013.