It is commonly recognized that some individuals can function well early in the morning while others have difficulty getting going. Those who start slowly in the morning are often able to maintain high energy levels late into the evening while early starters begin to fade. The differences between morning and evening types or larks and owls have long been documented by informal observation and personal experiences. Considerable scientific study now supports the fact that individuals can differ markedly in morningness-eveningness, also referred to as chronotype or circadian type. A few discoveries from scientific investigations are (a) chronotype is not a categorical trait, with a person being either in one group or the other; rather it is like most human traits (e.g. extraversion-introversion), normally distributed, with some individuals toward the extremes and most in the middle; (b) chronotype has clear biological correlates related to different timing of psychophysiological processes; (c) environmental pressures can push a person in a direction away from their chronotype, but only to a degree; (d) chronotype is relatively stable once a person reaches adulthood.
Schools in the U.S. start early, and children are expected to be alert and optimally functioning from the opening bell. Most children in elementary grades do reasonable well with an early start, but beginning in middle school and continuing through high school, there are sizeable numbers of children who struggle to attain full alertness and learning readiness in morning classes. Children begin to stay up later as they grow older, yet their rise times must adhere to the school schedule. Many factors can push bedtimes later, including social media, homework, and lax parental monitoring. The well documented adolescent phase delay means that post-pubertal teens have an especially hard time falling asleep early even when they go to bed early. All of these pressures are present as stable chronotypes begin to emerge. The difficulty of school work begins to increase in middle school and continues into high school. Teens who are not morning types will be unable to “get up to speed” for the first class of the day. Some teens and parents recognize this and try to avoid scheduling more challenging classes first period. On a recent visit to a small college, I learned that for some classes, students could go into a computer center any time of the day to take certain exams. That allows for accommodation to optimal time of cognitive functioning. Instituting such a plan in high schools is possible, but will be challenging given the inflexibility of schedules. But schedule inflexibility is, in my opinion, a deterrent to optimal academic achievement.