Researchers led by Reto Huber of the University Children's Hospital Zurich found when pubescent rats were administered caffeine, the maturing processes in their brains delayed. (Agencies)
In 30-day-old rodents, caffeine intake equating to three to four cups of coffee per day in humans resulted 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," said Huber.
When the brain then begins to mature during puberty, a large number of these connections are lost.
"This optimization presumably occurs during deep sleep. Key synapses extend, others are reduced; this makes the network more efficient and the brain more powerful," said Huber.
Huber's group of researchers administered moderate quantities of caffeine to rats over five days and measured the electrical current generated by their brains.
The deep sleep periods, which are characterized by slow waves, were reduced from day 31 until day 42, i.e. well beyond the end of administering caffeine.
Compared to the rats being given pure drinking water, the researchers found far more neural connections in the brains of the caffeine-drinking animals at the end of the study.
The slower maturing process in the brain also had an impact on behaviour: rats normally become more curious with age, but the rats consuming caffeine remained timid and cautious.
Researchers led by Reto Huber of the University Children's Hospital Zurich found when pubescent rats were administered caffeine, the maturing processes in their brains delayed.