Sleep - the yet underappreciated player in cardiovascular diseases: A clinical review from the German Cardiac Society Working Group on Sleep Disordered Breathing

Patients with a wide variety of cardiovascular diseases, including arterial and pulmonary hypertension, arrhythmia, coronary artery disease and heart failure, are more likely to report impaired sleep with reduced sleep duration and quality, and also, sometimes, sleep interruptions because of paroxysmal nocturnal dyspnoea or arrhythmias. Overall, objective short sleep and bad sleep quality (non-restorative sleep) and subjective long sleep duration are clearly associated with major cardiovascular diseases and fatal cardiovascular outcomes. Sleep apnoea, either obstructive or central in origin, represents the most prevalent, but only one, of many sleep-related disorders in cardiovascular patients. However, observations suggest a bidirectional relationship between sleep and cardiovascular diseases that may go beyond what can be explained based on concomitant sleep-related disorders as confounding factors. This makes sleep itself a modifiable treatment target. Therefore, this article reviews the available literature on the association of sleep with cardiovascular diseases, and discusses potential pathophysiological mechanisms. In addition, important limitations of the current assessment, quantification and interpretation of sleep in patients with cardiovascular disease, along with a discussion of suitable study designs to address future research questions and clinical implications are highlighted. There are only a few randomised controlled interventional outcome trials in this field, and some of the largest studies have failed to demonstrate improved survival with treatment (with worse outcomes in some cases). In contrast, some recent pilot studies have shown a benefit of treatment in selected patients with underlying cardiovascular diseases.