As we get older, we often get less than the recommended seven and a half to eight hours a night. That's because our ability to sleep for long periods of time and to get into the deep, restful stages of sleep decreases with age, according to Dr. Clete A. Kushida, director of the Stanford University Center for Human Sleep Research."Insomnia affects about 30-40 percent [of] the general population and chronic insomnia is roughly 10 to 15 percent," Kushida said.