Coffee-drinking teens may be harming their brain development, according to a new study from the Swiss National Science Foundation.

Researchers found that teenagers who drink three to four cups of coffee a day could be missing some of the deep sleep they need and therefore delaying their brain development. Scientists came to the conclusion after administering caffeine to 30-day-old rats and measuring how quickly their brains matured.

“The brain of children is extremely plastic due to the many connections,” Reto Huber of the University Children’s Hospital Zurich said. "This optimization presumably occurs during deep sleep. Key synapses extend, others are reduced; this makes the network more efficient and the brain more powerful."

For both humans and rats, deep sleep and the number of connections in their brains reaches their highest levels during puberty. When researchers administered moderate amounts of caffeine to rats over five days and monitored the electrical current generated by their brains, they found that deep sleep was reduced and they had fewer neural connections in their brains than the non-caffeine drinking rats.

The recent study published in the journal PLOS One also revealed a change in the rats’ behavior. Instead of being curious – a normal trait for their age – caffeinated rats were timid and cautious.

Caffeine is considered the “most widely utilized psychoactive substance among people of all age groups and cultural backgrounds,” the study states. It acts as a stimulant that can have serious side effects if taken in excess.

Over the past 30 years, caffeine consumption among teenagers has increased by 70 percent. In December 2010, the Journal of Pediatrics revealed that children ages 8 through 12 consuming an average of 109 milligrams of caffeine per day, in the 1980s that number was 38 milligrams.

Caffeine doesn’t necessarily mean coffee. Soda, energy drinks and tea are all caffeinated.

"These drinks are made for adults. When young children drink them, they consume a large quantity of caffeine for their body mass. At the minimum, they become wired - just as an adult would - and it might be difficult for parents to console them or calm them down," Bruce Ruck, from the New Jersey Poison Information & Education System at Rutgers New Jersey Medical School said in a statement. "Parents need to be aware of the risks and treat these drinks as they would a medication.”