Impact of heart failure on quality of sleep.

Chronic heart failure is an important health problem associated with a high mortality and morbidity. Appropriate treatment reduces mortality and leads to improved exercise tolerance but many patients report poor quality of sleep. Sleep studies of patients with heart failure suggest that sleep disordered breathing is experienced in 50% of patients and is a powerful predictor of poor prognosis. Sleep disordered breathing broadly comprises obstructive sleep apnoea, when upper airway instability causes mechanical obstruction to breathing; and central sleep apnoea, characterised by an absence of ventilatory effort. Sleep disordered breathing occurring in patients with heart failure is in most part attributable to central sleep apnoea and reflects uncompensated instability of the ventilatory feedback mechanism.