In sync with adolescence : The role of morningness-eveningness in development

At the start of every school day, it’s not an unfamiliar sight to see younger children bounding toward school, bright-eyed and bushy-tailed, ready to seize the day. In contrast, adolescents sometimes seem to sleepwalk toward their middle and high schools, often bleary-eyed, cantankerous, and less than enthusiastic to get down to work. Why the difference?