David Sellers, MD, ends his shifts when most physicians have their morning coffee. A nocturnist at Middle Tennessee Medical Center in Murfreesboro, he's on the hospital floor all night, ready to handle patient problems that go beyond the expertise of a nurse. Nights and weekends can be dangerous times for patients, according to multiple studies. The most recent—one that tracked the outcomes of 30 million patients over a five-year period—showed that patients admitted to hospitals on weekends have a 10% higher death rate. Sellers works every night of the week, including weekends. "This has been the most exciting thing I've done in medicine just because I'm able to focus on very sick patients, and I feel like I get them better and get them on their way out of the hospital, which is fulfilling," he said. Hospitals are increasingly counting on nocturnists to help them improve patient safety and response times. John Nelson, MD, a partner with Nelson Flores Hospital Medicine Consultants, coined the term nocturnist. By his estimate, there are probably 1,000 to 1,500 nocturnists working now compared with more than 100 a decade ago.