Sleep disorders affect a lot more people than most people realize — up to 20 percent of Americans in any given year suffer from a sleep problem, according to the National Institutes of Health. Many people who suffer from problems sleeping don’t even realize it. They may walk through the day feeling a little tired, unfocused, and unable to get started. These disorders and the resulting sleep deprivation interfere with work, driving, and social activities. The most common sleep disorders include insomnia, sleep apnea, daytime sleepiness, restless legs syndrome, and narcolepsy.