Lifestyle Medicine and SleepSleep is essential for life itself and optimal health. Sleep plays a significant role in virtually every aspect of living including metabolism, brain function, systemic physiology, appetite regulation and the function of the cardiovascular system as well as the immune system and hormonal systems. Lifestyle factors play a very important role in maintaining healthy sleep. For all these reasons, it is highly appropriate that healthy, restorative sleep is one of the six pillars of lifestyle medicine.As a cardiologist, I have been particularly interested in the area of sleep and its role in the normal functioning of the cardiovascular system. The American Heart Association (AHA) shares my level of interest and concern in this area. In fact, several years ago, the AHA listed a framework for lowering the risk of cardiovascular disease entitled "Life's Simple 7." Last year, the AHA modified this framework with an 8 th added factor and changed the mantra to "Life's Optimal 8." What do you think the 8 th criteria for cardiovascular health was? Normal, healthy sleep! In this issue of the American Journal of Lifestyle Medicine, we are delighted to present 4 articles on sleep and health which comprise the core of the theme of this issue's theme of "Sleep and Lifestyle Medicine." These articles range from a study on sleep