“Around the world, children get an hour’s less sleep than they did 30 years ago. . .The surprise is not merely that sleep matters—but how much it matters. . . . [C]hildren’s brains are a work in progress until the age of 21, and because much of that work is done while a child is asleep, this lost hour appears to have an exponential impact on children that it simply doesn’t have on adults.” -- Bronson and Merryman in Nurture Shock
As we enter a new school year, an important but too often neglected topic moves front and center--a topic that many parents dismiss with a sigh or a wave of the hand and one that children and adolescents respond to with an "arghh."
How Much Sleep Do You Really Need?
Newborns (0-2 months)
12 - 18 hours
Infants (3-11 months)
14 - 15 hours
12 – 14 hours
11 – 13 hours
10 – 11 hours
8.5 – 9.25 hours
Source: National Sleep Foundation
According to researchers and authors Po Bronson and Ashley Merryman in their chapter “The Lost Hour” (from Nurture Shock: New Thinking about Children), lack of sleep is a big deal—one that takes a profound toll on children and adolescents, undermining academic performance and emotional stability while contributing to the international obesity epidemic and the rise of ADHD.
Several key points from their research are particularly relevant to both parents and educators. I list the points below by topic—and offer a brief reflection.
· “. . .performance gap caused by an hour’s difference in sleep was bigger than the gap between a normal fourth-grader and a normal sixth-grader. Which as another way of saying that a slightly-sleepy sixth grader will perform in class like a mere fourth-grader.”
· “Sleep disorders can impair children’s IQ as much as lead poisoning.”
· “Teens who received A’s averaged about fifteen more minutes sleep than the B students, who in turn averaged fifteen more minutes than the C’s and so on.”
· “Sleep loss debilitates the body’s ability to extract glucose from the bloodstream. Without this stream of basic energy, one part of the brain suffers more than the rest—the prefrontal cortex, which is responsible for what’s called ‘Executive Function.’ Among these executive functions are the orchestration of thoughts to fulfill a goal, prediction of outcomes, and perceiving consequences of actions.”
· “The more you learned during the day, the more you need to sleep that night. . .[M]emories are enhanced and concretized during the night—new inferences and associations are drawn, leading to insights the next day.”
· “[T]he emotional context of a memory affects where it gets processed. Negative stimuli get processed by the amygdala; positive or neutral memories get processed by the hippocampus. Sleep deprivation hits the hippocampus harder than the amygdala. The result is that sleep-deprived people fail to recall pleasant memories, yet recall gloomy memories just fine.”
· “Sleep loss for teenagers is a special challenge. . .the circadian system—the biological clock—does a ‘phase shift’ that keeps adolescents up later. In prepubescents and grownups, when it gets dark outside, the brain produces melatonin, which makes us sleepy. But adolescent brains don’t release melatonin for another 90 minutes. . .Awakened at dawn by alarm clocks, teen brains are still releasing melatonin.”
· “Several scholars have noted that many hallmark traits of modern adolescence—moodiness, impulsiveness, disengagement—are also symptoms of chronic sleep deprivation. Might our culture-wide perceptions of what it means to be a teenager be unwittingly skewed by the fact they don’t get enough sleep?”
· "An hour more of sleep improved students' quality of life."
· “Dr. Eve Van Cauter discovered a ‘neuroendocrine cascade’ which links sleep to obesity. Sleep loss increases the hormone ghrelin, which signals hunger, and decreases its metabolic opposite, leptin, which suppresses apptetite.”
· “Those kids who get less than 8 hours sleep have a bout a 300% higher rate of obesity than those who get a full ten hours of sleep.”
· “. . .kids who don’t sleep well are often too tired to exercise—it’s been shown that the less sleep kids get, the less active they are during the day. So the net calorie burn, after a good night’s rest is higher.”
* * * * *
The research behind Bronson and Merryman's analysis is compelling--even overwhelming--taking up 10 full pages in the "Selected Sources and References" section of their book. There is little doubt that sleep represents a crucial component of children's and adolescents' health and well-being.
So, what to do?
One strong recommendation from sleep researchers Mary Carskadon (Brown University) and Mark Mahowald (Director of the Minnesota Regional Sleep Disorders Center) is to move the start time for high school later. When high schools in Edina, Minnesota changed from 7:25 a.m. to 8:30 a.m., SAT scores soared. And with young adults responsible for more than half of the 100,000 fall asleep automobile accidents annually, careful examination of later start times is well worth considering--even amid the many logistical hurdles, including bus schedules, sports schedules, and morning rush hour--all "adult convenience excuses" the researchers note.
An area of real potential for pre-high schoolers--children whose circadian system has not undergone the "phase shift" that keeps adolescents up later--is what Bronson and Merryman call the "slush hour," the last hour of a child's day. Bronson and Merryman describe this time as "a rush to sleep and a slush fund of potential time, sort of a petty cash drawer from which we withdraw ten minute increments." Worth considering is this: The research tells that increments of sleep time even as small as ten or fifteen minutes have an impact on the quality of children's lives.
If parents were to treat that final hour as the first hour of sleep--as an investment in their children's health and well being--as opposed to a slush fund that increases their children's sleep debt, that lost hour would be found. And our children would be the better for it.