Susanne Osadnik: One in six children and one in five adolescents in Germany suffer from stress, according to a study conducted by Bielefeld University. How do brain researchers define stress?

Martin Korte: Stress is a normal physiological phenomenon; there’s nothing unusual about it. It is the brain’s response to a particular situation. Perceiving a threat, the body enters a state of heightened alert. It releases elevated levels of cortisol, an anti-stress hormone that protects the body from the negative effects of excessive stress and helps it adjust to the prevailing conditions. It’s a useful mechanism – provided that the body then returns to its normal state.

SO: And if it doesn’t?

MK: Stress consumes a great deal of energy when the threat is perceived to persist for an extended period of time. This has a negative impact on overall well-being, and particularly on learning. Excessive levels of stress hormones in the blood make it impossible to absorb new information. The brain is blocked. This can happen in a testing situation, when people can become so agitated that they are unable to recall what they have learned.

SO: Do children experience stress differently than adults?

MK: There’s no way of measuring this objectively. Everyone experiences stress differently. This also holds true for children, who may respond in a variety of ways. Some children feel overwhelmed by excessively busy schedules. It’s important to look closely at a child’s schedule on a regular basis, and perhaps eliminate an activity or two in the interest of more free time – and perhaps even boredom.

SO: Children have a tendency to get bored quickly...

MK: Yes, but that’s not necessarily a bad thing. They need to learn to handle boredom in order to become active and creative. It isn’t good for them to be constantly entertained.

SO: What about homework? Children have to do it, but they don’t usually like it; indeed, it can be a daily battle for some children.

MK: There are children who have no trouble completing their daily assignments. Others feel constant pressure; for them, it’s important to take breaks and defuse the situation. Answers should be praised occasionally even when they aren’t perfect; it doesn’t always have to be about getting 100 percent right. Parents need to play a role, too. They should be realistic in their expectations of their children – and themselves. Nothing is more frustrating for the brain than unattainable goals.

SO: Parents often blame smartphones and other electronic devices for their children’s stress and poor grades.

MK: Digital media are not a bad thing per se. Parents need to stop viewing them as the enemy. What is harmful is excessive media use. We need to set limits – particularly for children, because they’re not able to judge how much they can handle.

By the way, multitasking is a myth. You can’t focus on multiple things at once and do justice to all of them. Children are never entirely present in the classroom. They’re always thinking about their friends, the games they like to play, their upcoming birthday. Or the latest news on their smartphones. All of this is very stressful.

SO: In your book about how children learn, “Wie Kinder heute lernen,” you also talk about the fact that children consume too much sugar. Does poor nutrition affect a child’s ability to learn?

MK: It has no impact on the brain or one’s ability to learn. But we are seeing a steady increase in the number of overweight children, and this is related to changes in eating habits and the amount of sugar in processed foods. Consuming too few fruits and vegetables and too much sausage, cheese, meat and sugar can lead to dangerous levels of obesity, which can result in chronic diseases – such as type 2 diabetes. Diabetes has an indirect effect on learning, as it is associated with poor performance, difficulty concentrating and chronic fatigue.

SO: That means people need to lose weight and become more active. What role does exercise play in boosting children’s brain development?

MK: Exercise is absolutely essential for both body and mind. Not only does physical activity keep your body in shape; it also keeps your mind healthy by stimulating the creation of nerve cells. That’s what the hippocampus does. Throughout our lives, it creates new nerve cells, and it’s also important for learning new information. The better the blood circulation, the better neurons are able to grow – which promotes our ability to concentrate. So exercise always has a positive effect; and that effect also applies to everyday learning.


Prof. Dr. Martin Korte is a biologist and brain researcher and director of the Zoological Institute, TU Braunschweig, Germany. His work focuses on the cellular aspects of learning and memory, neurotrophins and their receptors, synapses and plasticity in the hippocampus.


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