Patients with heart failure are known to demonstrate periodic respiration (PR) during sleep. The factors causing PR are not well known. We therefore studied 20 patients (aged 18-66 years) with idiopathic dilated cardiomyopathy. Full-night polysomnography and evaluation of respiration and transcutaneous oxygen saturation were performed. Hypercapnic ventilatory response (HCVR) was evaluated during daytime. The patients showed PR for 25 +/- 26% (mean +/- standard deviation) of total sleep time. During PR, oxygen desaturated 7.1 +/- 4.6%. Sleep was impaired. HCVR was normal. Oxygen desaturation during PR was predicted by HCVR (r = 0.47, P < 0.05) and left atrial diameter (r = 0.60, P < 0.05). The time period of PR expressed as a fraction of total sleep time was correlated with HCVR (r = 0.45, P < 0.05) and left atrial diameter (r = 0.51, P < 0.05). In conclusion, PR with oxygen desaturation, arousals, and impaired sleep was observed in stable heart failure. HCVR and left heart dimensions were related to PR. These findings confirm the concept of a feedback loop describing respiratory control in PR.