they don’t get their naps. Adults spend about a third of their time asleep, and that doesn’t appear to be an enormous waste of valuable time. Experiments where people have tried to stay awake for as long as 200 hours have induced hallucinations and paranoia. If adults have troubling sleeping—and according to a 2005 poll from the National Sleep Foundation, 57 percent of Americans do—nearly every aspect of their lives is affected, leaving them prone to making mistakes at work, having car accidents, being too sleepy for sex.
Sleep, obviously, offers muscles and other parts of the body a chance to rest. But not the brain: measurements of its electrical activity reveal that it’s hardly dormant. Still, until 1953, when two researchers who were studying children’s sleep patterns described REM sleep for the first time, scientists assumed that the brain was inactive during sleep. But exactly why sleep is so important, regardless of your age, and what sleep means to the brain are questions scientists cannot answer yet. Perhaps sleep helps consolidate learning (more on that later in “Sleep and Learning: Caffeine in Your Beer,” on page 43).
TEENAGERS: WHAT WERE YOU THINKING!
In a child’s first year, the brain triples in size, until it’s almost three quarters of the size of an adult’s. The brain achieves its full growth at about age 17. The number of neurons doesn’t increase, but the number of synapses do as children imitate, learn, remember, and add to their experiences. By adulthood, the brain has 100 trillion synapses. But before adulthood comes adolescence, when the brain is flooded with hormones. Neurologists only recently have confirmed what every parent knows: The teenage brain is indeed different. In the teenage brain, the prefrontal cortex—the center of reasoning and impulse control—is still forming. In some people, that maturation may notoccur until they are 25 years old. That’s why so many teenagers have trouble understanding the consequences of their impulsive, destructive behavior. That’s why, as every parent can tell you, teenagers are impulsive, emotionally erratic, and liable to make poor decisions. The answer is simple: The section of the brain that can foresee the future, the part that can predict the consequences of actions, is not fully developed.
Every parent also knows that teenagers have a terrible time getting up in time for school and on weekends, preferring to sleep into the afternoon. Neuroscientists now know that teens aren’t being lazy—they really do need more sleep. Some schools have even pushed the start of the school day later to take into account the adolescent need for sleep.
SEEING INSIDE THE BRAIN
We’ve been able to learn more about the adolescent brain because today, we don’t have to drill into the brain to find out about it, as early peoples did. We have new technology that allows us to see what the brain looks like and what it’s doing. And that’s an excellent advance because the brain is delicate, and once a neuron is destroyed, it’s gone forever—though the brain often is able to compensate for the loss. Neurosurgeons even have a pithy saying: “You’re never the same once air hits your brain.”
In 1917, László Benedek, a Hungarian neurologist, took the first pictures of the living brain with what was then the brand-new technology of X-rays. German physicist Wilhelm Roentgen won the Nobel Prize for discovering X-rays, in 1895, making it possible to see structures inside the body without surgery. By 1936, Benedek had come up with the idea of making three-dimensional X-ray pictures of the brain. But X-rays can only show large features of the brain, such as tumors; they cannot show the different layers inside the brain. Nor can they capture the brain’s activity and changes, which last only a split second.
In the 1970s, Benedek’s idea had been developed into the computerized axial tomography (CAT) scanner—the CAT scan, which uses X-rays
Sleep, obviously, offers muscles and other parts of the body a chance to rest. But not the brain: measurements of its electrical activity reveal that it’s hardly dormant. Still, until 1953, when two researchers who were studying children’s sleep patterns described REM sleep for the first time, scientists assumed that the brain was inactive during sleep. But exactly why sleep is so important, regardless of your age, and what sleep means to the brain are questions scientists cannot answer yet. Perhaps sleep helps consolidate learning (more on that later in “Sleep and Learning: Caffeine in Your Beer,” on page 43).
TEENAGERS: WHAT WERE YOU THINKING!
In a child’s first year, the brain triples in size, until it’s almost three quarters of the size of an adult’s. The brain achieves its full growth at about age 17. The number of neurons doesn’t increase, but the number of synapses do as children imitate, learn, remember, and add to their experiences. By adulthood, the brain has 100 trillion synapses. But before adulthood comes adolescence, when the brain is flooded with hormones. Neurologists only recently have confirmed what every parent knows: The teenage brain is indeed different. In the teenage brain, the prefrontal cortex—the center of reasoning and impulse control—is still forming. In some people, that maturation may notoccur until they are 25 years old. That’s why so many teenagers have trouble understanding the consequences of their impulsive, destructive behavior. That’s why, as every parent can tell you, teenagers are impulsive, emotionally erratic, and liable to make poor decisions. The answer is simple: The section of the brain that can foresee the future, the part that can predict the consequences of actions, is not fully developed.
Every parent also knows that teenagers have a terrible time getting up in time for school and on weekends, preferring to sleep into the afternoon. Neuroscientists now know that teens aren’t being lazy—they really do need more sleep. Some schools have even pushed the start of the school day later to take into account the adolescent need for sleep.
SEEING INSIDE THE BRAIN
We’ve been able to learn more about the adolescent brain because today, we don’t have to drill into the brain to find out about it, as early peoples did. We have new technology that allows us to see what the brain looks like and what it’s doing. And that’s an excellent advance because the brain is delicate, and once a neuron is destroyed, it’s gone forever—though the brain often is able to compensate for the loss. Neurosurgeons even have a pithy saying: “You’re never the same once air hits your brain.”
In 1917, László Benedek, a Hungarian neurologist, took the first pictures of the living brain with what was then the brand-new technology of X-rays. German physicist Wilhelm Roentgen won the Nobel Prize for discovering X-rays, in 1895, making it possible to see structures inside the body without surgery. By 1936, Benedek had come up with the idea of making three-dimensional X-ray pictures of the brain. But X-rays can only show large features of the brain, such as tumors; they cannot show the different layers inside the brain. Nor can they capture the brain’s activity and changes, which last only a split second.
In the 1970s, Benedek’s idea had been developed into the computerized axial tomography (CAT) scanner—the CAT scan, which uses X-rays
Similar Books
Why Dogs Chase Cars
George Singleton
The Devil's Dust
C.B. Forrest
Shattered
Gabrielle Lord
The Rose Garden
Susanna Kearsley
BloodlustandMetal
Lisa Carlisle
House of the Rising Sun
Kristen Painter
Who Walks in Flame
David Alastair Hayden
India Dishonoured: Behind a Nation's War on Women
Sunny Hundal
The Slave Market of Mucar
Lee Falk
