People have been studying for years about what intelligence is, what part of the brain is involved in “intelligence”, and how can we measure it. In general, intelligence is the ability to learn and to recall or remember what we have learned. In the 1960’s it was suggested that there were two “systems” of intelligence, fluid intelligence and crystallized intelligence. Fluid intelligence involves the ability to understand, to reason, and to solve problems. Crystallized intelligence involves recalling stored knowledge and past experiences.
With the increasing ability to look at the brain and to measure the activity of the parts of the brain, it has been noted that fluid and crystallized intelligence rely on different brain systems. These systems are distinct but interrelated when doing a task. Various tools are used to measure intelligence, and new research is evaluating how to improve intelligence.
One recent study looked at how sleep can affect the developing brain. Everyone knows that insufficient sleep makes a person groggy, irritable and sometimes unable to function well. Something to consider when cramming all night for a test. More concerning is a new study shows insufficient sleep may hurt neurodevelopment in ways that can be measured on brain scans and tests over time.
Research recently published in The Lancet Child and Adolescent Health (Jul 29, 2022) found that 9-and 10-year olds who did not get at least 9 hours of sleep most nights tend to have less gray matter and smaller areas of the brain that is responsible for attention, memory and inhibition control. They also found a relationship between insufficient sleep and disrupted connections between the basal ganglia and cortical regions of the brain. These disruption appeared to be linked to depression, thought problems, and impairments in crystallized intelligence, the type of intelligence that depends on memory.
This study had over 6000 children with about 3000 in the sufficient sleep group and 3000 who got at least 9 hours of sleep. The researchers looked at 42 behavioral outcomes, 32 of which were significantly different between the two groups. While the different results were called modest, they found that sleep duration effect on crystallized intelligence was twice that for fluid intelligence.
Dr. Ariel Williamson, a pediatric sleep expert, found that this study is consistent with previous understanding of the importance of sufficient sleep for child well-being and hopes future studies will help evaluate the impact of quality of sleep, the timing of bedtime and the timing of school starting. To promote healthy sleep, parents should keep a strict routine for their children, such as a regular bedtime and no electronic devices in the bedroom. More physical activity during the day should help.
High levels of stress and/or depression in children can also cause sleep problems and should be addressed in the process of getting sufficient sleep. Dr. Williamson states that “sleep is a pillar of health” and even extending sleep by 20-30 minutes can make a difference. Good sleep is smart.