Patients with heart failure (HF) often suffer from sleep-related breathing disorders (SRBD) like Cheyne-Stokes respiration (CSR). Cardiac resynchronization therapy (CRT) improves myocardial function and exercise capacity in patients with HF and conduction disturbances. As CRT has been shown to reduce CSR in patients with HF, it is not clear whether CRT improves quality of life and symptomatic depression by improvement of apnea/hypopnea index (AHI) and sleep quality. Forty-two HF patients with conduction disturbance before CRT were screened for CSR and evaluated for sleep quality [Pittsburgh Sleep Quality Index (PSQI)], quality of life score [36-item short form (SF-36)], depression, and exercise capacity (VO2 peak) and ejection fraction (EF). Eighteen patients (three females, age 61+/-10, body mass index 24+/-4 kg m(-2), EF 24+/-4%, QRS complex duration 156+/-32 ms) presented CSR with an AHI of 18+/-8 (11 CSR, 7 mixed). Fourteen patients showed no SRBD (PSQI<5,AHI<5). All patients received CRT and were reevaluated after 18+/-7 weeks. CSR worsen quality of life in seven of eight terms compared to patients without SRBD. Symptomatic depressive symptoms (Beck Depression Inventory>10) were only present in patients with CSR. CRT results in improvement of peak VO2 and EF. There was no difference between patients with CSR and without SRBD on exercise capacity or EF under CRT, whereas CRT led to a significant decrease in AHI (18+/-8 to 3+/-2, p<0.0001), PSQI (18+/-4 to 6+/-3, p=0.0007), with reduction of depression score (12+/-3 to 4.8+/-3, p=0.004). In patients with HF, CSR is associated with symptomatic depressive syndromes and impaired quality of life. CRT reduced CSR with improvement of sleep quality and symptomatic depression.