Tired kids are crabby kids, and obviously they don't do very well in school. But a new study in Japan suggests that a tired brain responds differently depending on how old the child is. Two similar sized groups of 4-6th and 7-9th graders were tested on everything from brain processing speed to memory and attention. Children who were tired in the younger group scored lower on an item called motor processing, meaning that they responded slower to commands like pointing their finger at a target. The older children had problems with working memory and two types of attention- alternating and divided, when they were fatigued. Working memory is the ability to hold a concept in your head as you're working on a problem- like how many days Mary can work and the fact that Bill can't work on the same days as Mary when filling out a schedule. Alternating attention is easy to understand- it's the ability to switch from working on a math problem to working on a reading one. Divided attention is commonly referred to as multi-tasking, the ability to simultaneously pay attention to two things at once.
It seems that as our brains are developing, being tired affects them differently. We can imagine what this says about our school day if the children haven't had a full night's sleep. Younger children will drag their feet, be a little uncoordinated, and have a hard time staying still. Older kids will be able to physically hide their fatigue better because it doesn't impact their brains that way. However, they'll still have a hard time with that broad concept of "focusing." It's interesting to see that several of these tired brain symptoms are also ADHD symptoms- the fidgeting, the poor multi-tasking, the difficulty in switching the brain into different gears for different tasks. It's almost as if the ADHD brain is in a constant state of chronic fatigue.
Kei Mizuno, Masaaki Tanaka, Sanae Fukuda, Kyoko Imai-Matsumura, Yasuyoshi Watanabe (2011). "Relationship between cognitive functions and prevalence of fatigue in elementary and junior high school students." Brain & Development 33 (6): 470-479. doi:10.1016/j.braindev.2010.08.012
