Shankar and lead writer Charumathi Sabanayagam, MD, analyzed data from 30,397 adults who participated in the 2005 National Health Interview Survey, which collected information on demographic elements, socioeconomic characteristics, health and lifestyle. Sleep duration was assessed by the question, On average, how many hours of sleep do you enter a 24-hour period? Participants reported 2,146 cases of cardiovascular disease, which was defined as a physician medical diagnosis of angina, cardiovascular system disease, heart attack or stroke. Related StoriesNew Cleveland Clinic research shows bariatric medical procedures is safe option for managing type 2 diabetes in obese or mildly obese patientsStudy explores diabetes screening for patients with serious mental illnessInnovative senior high school health program helps students maintain healthier weights, relieve depressionAn elevated but much less dramatic risk of cardiovascular disease also was discovered with reported daily sleep durations of six hours and eight hours .But those admitted on a Saturday were 12 percent more likely to die within a week. And all sufferers admitted at the weekend for elective surgery treatment were much more likely to die within thirty days across the panel than those admitted on additional days of the week, the findings showed. The researchers of the analysis speculate on the reasons for the findings, pointing out that nobody single factor is going to be responsible. They claim that particular diagnoses and procedures could be particularly sensitive to reduced usage of test results and diagnostics at weekends. Similarly, weekend staff might be fewer in number and less experienced, while sufferers requiring urgent treatment may need to wait longer, which can affect the success of any interventions and treatment. Professor Lilford and Dr Chen had been asked to create provide expert comment because of their work on a project to judge NHS England's policy drive for seven-day services.