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More efficient learning thanks to sleep

Young children, adolescents and students may experience learning difficulties as a result of lack of sleep. Dr Kristiaan van der Heijden investigates sleep problems and solutions for various age groups.

Sleep plays a central role in human life; we sleep in total an average of 26 years. During sleep, all kinds of important processes take place in the brain, including repairing damaged cells, eliminating waste and processing information in memory. Ten percent of the Dutch population suffer from sleep problems, and researchers have identified more than 80 different sleep disorders. Kristiaan van der Heijden investigates disruptions in the biological clock, and their consequences for children and adults, one of which is a reduced ability to learn. Below are a few important discoveries regarding sleep, by age group:

From 6 to 12

Together with other researchers, Van der Heijden discovered that when children aged 6 to 12 don’t sleep enough they primarily experience problems with planning, behaviour, and multi-tasking. ‘It’s interesting: unlike adults, sleep deficit in children of this age seems to have no effect on memory and learning ability. It’s unclear why this is the case. Maybe children need that ability to learn so much that their brain processes information equally well during the day.’

Van der Heijden also discovered that children aged 10 to 12 perform less well in the early morning. ‘They perform less well on complex tasks at 8.30 a.m. than an hour and a half later. These children also performed better at 1 p.m. than at 8.30 a.m. Incidentally, performance may also be related to children’s temperament, as is apparent from one of his other studies. ‘We looked at the relationship between sleep duration and how well children were able to complete tests. For introverted children in particular, it turned out that long periods of sleep were detrimental; when they slept too long they performed less well on tasks.’

A possible explanation for this finding is that these children have a high alertness and anxiety level. ‘Sleeping a lot further increases your sensitivity to environmental stimuli. Children with a high level of alertness are already sensitive to environmental stimuli, and a long night may ‘double’ this effect. They become even more alert, and therefore unable to focus on completing a task.’


Many parents will recognise the problem of the adolescent who has trouble getting out of bed in the morning. ‘In adolescence the bio-rhythm shifts by one hour, as a result of hormonal changes,’ explains Van der Heijden. ‘This shift is problematic for social reasons because even though adolescents are becoming night owls, they’re still expected to get up early for school. The biological clock can be shifted using light stimuli. If you have trouble waking up in the morning, it helps to use a bright light with a blue spectrum in the morning.’ An additional tip from Van der Heijden: don’t let adolescents sleep in too long after a night out with friends. 'This shifts the biological clock even further, and it’s difficult to shift it “back”.’

Adolescents can’t help enjoying sleeping in; it’s their hormones.

Students: performance suffers from poor sleep hygiene

Van der Heijden has shown that students who sleep less well get poorer grades. This is due among other things to the fact that students are often unaware of healthy and unhealthy sleeping habits. ‘One of the most important misunderstandings is that it’s good to exercise shortly before going to sleep. Exercise is great during the day, but if you do it shortly before going to sleep it will keep your system awake and alert. If you do it on a regular basis, you will shift your biological clock and have trouble waking up in the morning.’

Van der Heijden also investigates sleep problems in babies and older people. In the coming months he will be focusing more on the relationship between sleep disorders and children with psychological disorders such as ADHD.

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