Whether it's electric lights, addiction to digital devices, or just the fast pace of modern life, one thing is clear: it seems to be getting harder to get a good night's sleep. Almost 50 percent of Americans say they can't get the zzz's they need. To understand why many are sleep deprived, take a deep dive into the body's control center, the brain, and follow the work of researchers who are unraveling the secrets of sleep.