the first study on how napping affects the cortisol awakening response, a burst of hormone secretion known to take place shortly after morning awakening. They showed that children produce this response after short naps in the morning and afternoon, though not in the evening, and it may be adaptive in helping children respond to the stresses of the day.
By experimentally restricting sleep in young children, and then analyzing their behavior in putting puzzles together, Dr. LeBourgeois’ group also is quantifying how napping — or the lack of it — affects the ways that children respond to situations. “Sleepy children are not able to cope with day-to-day challenges in their worlds,” she said. When children skip even a single nap, “We get less positivity, more negativity and decreased cognitive engagement.”
But for parents and scientists alike, there are many unanswered questions: When is it too early to give up a nap? Too late to hold on to a nap? How do domestic patterns and cultural norms affect the circadian and homeostatic processes?
“I think there’s a dire need for adults in general to be in tune with individual children’s physiology,” Dr. LeBourgeois said. “What are the capabilities, and what are the limits?”
This everyday childhood behavior, commonly a source of family struggle, is the product of cultural and familial expectations as well as complicated biology, which changes as the child grows.
“If the child is stopping the napping, that represents a process of neurological maturation,” Dr. Jenni said. “The ability to tolerate wakefulness is an indication that the brain is maturing.”