less than their thinner counterparts. According to the North American Association for the Study of Obesity, people who get 10 or more hours of sleep are 11 percent less likely to become obese. Those who sleep six hours a night are 23 percent more likely to become obese and those who get five hours of sleep are 50 percent more likely to be obese. The exhausted folks who log only four or fewer hours a night are 73 percent more likely to be obese than those who get adequate rest.
Sleep researcher James Gangwisch reports that the relationship between sleep and obesity applies to children and adolescents as well as adults. A recent study of 12 young men linked the reduction in leptin associated with sleep loss to increased hunger and appetite, especially for high-calorie, high-carbohydrate foods. And we all know that exhausted teens who need to live by society’s schedule often survive on fat-filled fast food because they don’t have the time to eat lower-calorie, well-balanced meals. If your teen is overweight, more exercise and less eating are certainly in order. But a good night’s sleep, night after night after night, may also contribute to a healthier, fitter body and the prevention of a lifetime of obesity—which in turn can prevent depression, to which obesity is often linked. Adequate sleep can also lower the risk for diabetes, which increases with weight gain and with the body’s inability to metabolize sugar properly. In addition it can help to prevent sleep apnea, a sleep disorder that can accompany obesity. (For more on the link between sleep loss and diabetes, see Chapter 11; for more on the connection between sleep loss and sleep apnea, see Chapter 10.)
OK, I know—it’s already very clear to you that teens can be moody beings. You’ve seen your daughter swing more than once from an exuberant high to grouchy prickliness to barely conversant back to excited and alive. The many changes of adolescence can make teenagers emotional and volatile, and they can also be easily wounded and much more fragile than they appear. Even when they’re well rested, teens can leap up and down the emotional scale. When they’re sleep deprived, their emotions can tend toward the negative side and be much harder for them to control.