Sleep’s Influence on “Intelligence” and School Performance
Please note that this section contains my personal notes from my readings on this topic.
In 1925, the father of the Stanford-Binet Intelligence Test, Dr. Lewis M. Terman, published his landmark book, Genetic Studies of Genius. He compared approximately 600 children with IQ scores over 140 to a group of almost 2,700 children with IQ scores below 140. For every age examined, the gifted children slept longer!
Even seventy-nine years later, Dr. Terman’s study stands apart in design, execution, and thoroughness. A 1983 scientific sleep laboratory study from Canada has provided objective evidence confirming Terman’s result, that children of superior IQ had greater total sleep time. Both studies agreed that brighter children slept about thirty to forty minutes longer each night than average children of similar ages.
Two years later, about 5,500 Japanese schoolchildren were studied, and those with better grades slept longer!
Another study from the University of Louisville School of Medicine examined a group of identical twins that were selected because one twin slept less than the other. At about ten years of age, the twin with the longer sleep pattern had higher total reading, vocabulary, and comprehension scores than the twin with the shorter sleep pattern.
Please don’t think that it has no lasting effect when you routinely keep your child up too late — for your own pleasure after work or because you want to avoid bedtime confrontations — or when you cut corners on naps in order to run errands or visit friends. Once in a while, for a special occasion or reason, it’s okay. But day-in, day-out sleep deprivation at night or for naps, as a matter of habit, could be very damaging to your child. Cumulative, chronic sleep losses, even of brief duration, may be harmful for learning.
Children diagnosed with attention deficit hyperactivity disorder or learning disabilites have been shown to have sleep-related difficulties, though we don’t know which came first. Nevertheless, one careful intervention study showed that improvements in sleep dramatically improved peer relations and classroom performance.
More Creativity and Richer Life!
Research on creative adults supports the concept that originality of ideas and the quality of experiences suffer when you cut back on sleep. What you lose in waking time is made up in terms of a richer life.
One recent study examined the effects of a single night of sleep restriction in a group of children between ten and fourteen years old. The researchers noted that there were impairments in verbal creativity, abstract thinking / concept formation, and in complex problem solving. These higher cognitive abilities appear to be essential for academic performance and success. In contrast, there were no deficits on rote performance or less-complex memory and learning tasks. The ability to maintain routine performance despite being sleepy is familiar to every adult who sometimes gets very tired but nevertheless is able to perform the routine aspects of his or her job fairly well. My interpretation of this study is that chronic sleepiness in infants and young children impairs cognitive development, but this will not become apparent until the child is much older and challenged by more complex tasks.