At least 8.6 million Americans take prescription sleeping pills to catch a few winks of sleep, according to the Centers for Disease Control and Prevention, the first federal health study to focus on actual use. Between 2005 and 2010, about 4 percent of adults in the U.S. took prescription drugs such as Lunesta and Ambien, government researchers, tracked down 17,000 people and looked into their medicine cabinets. About a quarter of those studied suffered from serious sleep problems. The report is the latest evidence that a good night's rest is becoming more elusive for Americans. Overall, between 50 and 70 million Americans suffer from sleep disorders, according to the Institute of Medicine. Women were also more likely to rely on sleeping pills than men, the study found.