Background: The present study determines the influence of sleeping position on central sleep apnea (CSA) in patients with heart failure (HF). Methods: The apnea/hypopnea index (AHI) during different body positions while asleep was examined by cardiorespiratry polygraphy in 71 patients with HF (ejection fraction <45%). Results: Twenty-five of the patients having predominantly CSA (central apnea index >= 10/h) with a lower obstructive apnea index (<5/h) were assigned to groups With positional (lateral to Supine ratio of AHI <50%. n = 12) or non-positional (ratio >= 50%, n = 13) CSA. In the non-positional group the BNP level was higher, the ejection fraction was lower and the trans-tricuspid pressure gradient was higher than in the positional group. Multiple regression analysis revealed more advanced age (p = 0,006), log(10) BNP (p = 0.017) and lung-to-finger circulation time (p = 0.020) as independent factors of the degree of positional CSA. Intensive treatment for HF changed CSA from non-positional to positional in all eight patients tested. Single night of positional therapy reduced CSA (p < 0.05) and BNP level (p = 0.07) in seven positional patients. Conclusion: As cardiac dysfunction progresses, severity of CSA also increases and positional CSA becomes position-independent. Positional therapy Could decrease CSA, thereby having a valuable effect on HF. (C) 2009 Elsevier B.V. All rights reserved.