Learning in your sleep - is that possible?
After school, Luis learns French words and for the geography test. The 14-year-old goes to bed at 9 pm. The following night helps to decide whether he will remember what he has learnt. Enough sleep and, above all, a restful deep sleep are crucial. Why we sleep is a question that has not yet been scientifically clarified - even though specialists agree that sleep is essential for the immune system, metabolism and cognitive performance of the brain.
Sleep and learning has been one of the main research areas in sleep research in recent decades, explains Reto Huber, Scientific Director of the Centre for Sleep Medicine at Zurich Children's Hospital. «Sleep is more than just a resting phase; it makes an independent contribution to learning, memory and the processing of experiences,» says Huber. It is scientifically undisputed that sleep contributes to learning success: «If you learn something before going to bed that will be tested the next day, you achieve an improvement of 10 to 20 per cent,» explains Huber - at least in adults.
for adults.
More important than how long you sleep is how good and deep your sleep is
The picture is more blurred for children and adolescents. This is because sleep is a complicated matter that is determined by several factors. Firstly, the individual sleep needs of children and adolescents. Secondly, there are short sleepers and long sleepers. And thirdly, there are so-called chronotypes: the owls, who don't like to go to bed before 11 pm and don't get up in the morning, and the larks, who like to go to bed early and are already very alert at seven in the morning. What's more: During puberty, the ability to stay awake longer and get up later generally increases.
But even more important than the duration of sleep is the intensity of sleep, i.e. how good and deep the sleep is. The first half of the night is crucial. Deep sleep is characterised by so-called slow waves, known in technical jargon as slow wave streams (SWS). They are the measure of sleep quality; the clearer and the more slow waves, the deeper the sleep phase. The decisive factor is that the normally continuous activity of the neurones is interrupted for a few hundred milliseconds. When many neurons do this, it generates the slow brain waves, the slow-wave currents. «We know from a large number of studies that these slow waves are particularly important for learning processes in the brain,» explains the sleep expert. If these currents are disturbed by external stimuli, for example, test subjects show learning deficits. Compared to undisturbed sleepers, they are less able to remember memorised word pairs the next morning.
What are slow wave currents?
These slow waves are particularly interesting because they are linked to brain development. This changes significantly during childhood and adolescence. Interestingly, slow waves are always particularly active in the region of the brain where a maturation process is taking place. «This can be seen, for example, in the sleep of 6 to 8-year-olds; at this age, children sleep so incredibly deeply that it is almost impossible to wake them up,» explains Reto Huber. The increasing maturation of the frontal lobe means that children can increasingly control themselves, control their emotions and push out their needs. This enables them to concentrate better and learn in a focussed way.
It is sometimes difficult for parents to find out how much sleep their child needs.
In adolescents, the front parts of the cerebrum, which are needed for decision-making and higher cognitive performance, are remodelled. «Only the relevant connections that are important for the functionality of the brain in adolescence survive,» says Reto Huber. Over time, teenagers have a less dense but all the more efficient network of nerve cells.
And just as the wave of remodelling of the brain happens from the back to the front, these SWS patterns also change. This means that teenagers sleep less because their ability to stay awake for longer increases. But they sleep relatively deeply. Slow waves are therefore important for memory performance. Learning content that is memorised in the evening is better remembered in the morning. But the big question is: what happens when young people sleep too little? «Of course there is a loss of performance,» explains Reto Huber.
Getting enough sleep is important
However, the limit is very individual and depends on the individual's performance, as not all cognitive abilities go awry. Science has not proven whether eight hours a day is really necessary." However, we can see that teenagers sleep much more at the weekend than during the week. «This shows that a certain need is being neglected during the week.»
It is sometimes difficult for parents to work out how much sleep their child needs. According to Reto Huber, you can use holiday times as a guide if young people can live according to their own rhythm. «If someone always goes to bed at 11 pm and doesn't get up until 11 am, it's clear that this person needs more than seven hours' sleep.»
However, young people make up for their lack of sleep on the one hand by sleeping more deeply; they make up for a sleep deficit with a few nights of deep sleep. On the other hand, they have to catch up on sleep more often, especially at the weekend or on holiday. And Luis? He slept well the night before the test. He brought home a 5.5 in the geography test and still knew the French words the next day. A good night's sleep was followed by a successful day of learning.
