In particular, introverts may have higher levels of cortical arousal, giving them greater resistance to sleep deprivation.

ADHD kids have a hard time with working memory because they lack adequate cortical arousal, and Rapport believes that their squirms and fidgets help stimulate that arousal.

According to psychologist Mark Rapport of UCF, squirming and fidgeting can be a way children maintain their cortical arousal — especially their working memory — when faced with a dull task.