A child’s brain, and its body as well, are in the prime of their vigor
during the morning hours. From nine till noon, therefore, should be the
period of the hardest mental or physical work he undergoes. Evening
preparation of lessons is harmful, not only because it tends to bring
into a state of high activity the brain, which shortly should be quiet
and ready to sink into slumber, but also because it throws hard work on
an already fatigued organ. Much of the nervousness, debility, and
insomnia so common among school children can be traced to evening
preparation.