WASHINGTON – Memo to that Massachusetts school where children in physical education classes jump rope without using ropes: Get some ropes. And you – you are about 85 percent of all parents – who are constantly telling your children how intelligent they are: Do your children a favor and pipe down.

These are nuggets from “NurtureShock: New Thinking About Children” by Po Bronson and Ashley Merryman. It is another book to torment modern parents who are determined to bring to bear on their offspring the accumulated science of child-rearing. Modern parents want to nurture so skillfully that Mother Nature will gasp in admiration at the marvels their parenting produces from the soft clay of children.

Those Massachusetts children are jumping rope without ropes because of a self-esteem obsession. The assumption is that thinking highly of oneself is a prerequisite for high achievement. That is why some children’s soccer teams stopped counting goals (think of the damaged psyches of children who rarely scored) and shower trophies on everyone. No child at that Massachusetts school suffers damaged self-esteem by tripping on the jump rope.

But the theory that praise, self-esteem and accomplishment increase in tandem is false. Children incessantly praised for their intelligence (often by parents who are really praising themselves) often underrate the importance of effort. Children who open their lunchboxes and find mothers’ handwritten notes telling them how amazingly bright they are tend to falter when they encounter academic difficulties. Also, Bronson and Merryman say that overpraised children are prone to cheating because they have not developed strategies for coping with failure.

“We put our children in high-pressure environments,” Bronson and Merryman write, “seeking out the best schools we can find, then we use the constant praise to soften the intensity of those environments.” But children excessively praised for their intelligence become risk averse in order to preserve their reputations. Instead, Bronson and Merryman say, praise effort (“I like how you keep trying”): It is a variable children can control.

They often cannot control cars. In 1999, a Johns Hopkins University study found that some school districts that abolished driver’s education courses experienced a 27 percent decrease in auto accidents among 16- and 17-year-olds. Odd.

Not really. Bronson and Merryman say driver’s ed teaches the rules of the road and mechanics of driving, but teenagers are in fatal crashes at twice the rate of other drivers because of poor decisions, not poor skills. The wiring in the frontal lobe of the teenage brain is not fully formed. Driver’s ed courses make getting a license easy, thereby increasing the supply of young drivers who actually have holes in their heads.

Their unfinished heads should spend more time on pillows. Only 5 percent of high school seniors get eight hours of sleep a night. Children get a hour less than they did 30 years ago, which subtracts IQ points and adds body weight.

Until age 21, the circuitry of a child’s brain is being completed. Bronson and Merryman report research on grade schoolers showing that “the 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.” In high school there is a steep decline in sleep hours, and a striking correlation of sleep and grades.

Tired children have trouble retaining learning “because neurons lose their plasticity, becoming incapable of forming the new synaptic connections necessary to encode a memory. … The more you learned during the day, the more you need to sleep that night.”

The school day starts too early because that is convenient for parents and teachers. Awakened at dawn, teenage brains are still releasing melatonin, which makes them sleepy. This is one reason why young adults are responsible for half the 100,000 annual “fall asleep” automobile crashes. When Edina, Minn., changed its high school start from 7:25 a.m. to 8:30 a.m., math/verbal SAT scores rose substantially.

Furthermore, sleep loss increases the hormone that stimulates hunger and decreases the one that suppresses appetite. Hence the correlation between less sleep and more obesity.

Bronson and Merryman slay a slew of myths. But perhaps the soundest advice for parents is: Lighten up. People have been raising children for approximately as long as there have been people. Only recently – about five minutes ago, relative to the long-running human comedy – have parents been driving themselves to distraction by taking too seriously the idea that “as the twig is bent the tree’s inclined.” Twigs are not limitlessly bendable; trees will be what they will be.

© 2010, Washington Post Writers Group