Effects of the Buteyko breathing technique on sleep quality, fatigue, and oxygen saturation in patients with acute coronary syndrome: a randomized controlled trial.
Safarabadi M, Farsani S, et al. • BMC cardiovascular disorders • 2026
Although modest improvements occurred in sleep, fatigue, and oxygenation, changes were clinically insignificant with no between-group differences; thus, the Buteyko breathing intervention cannot be recommended over standard evidence-based care.
Key Findings
Results
Both the Buteyko breathing group and the diaphragmatic breathing control group showed statistically significant within-group improvements in sleep quality, fatigue, and oxygen saturation over six weeks.
PSQI scores improved by -0.82 in the intervention group and -1.16 in the control group (both p < 0.05).
MFI-20 fatigue scores improved by -2.44 in the intervention group and -3.96 in the control group (both p < 0.05).
SpO₂ increased by +0.40 in the intervention group and +0.42 in the control group (both p < 0.05).
Both groups received their respective breathing techniques alongside routine care for six weeks.
Results
There were no statistically significant between-group differences in sleep quality after the intervention.
Mean difference in PSQI between groups: MD = -0.36 (95% CI: -1.14 to 0.43; p = 0.37).
Effect size was uniformly small (Cohen's d ≤ 0.28).
90 patients were randomized equally to intervention and control groups with comparable baseline characteristics.
Results
There were no statistically significant between-group differences in fatigue scores after the intervention.
Mean difference in MFI-20 fatigue scores between groups: MD = 0.40 (95% CI: -3.47 to 4.27; p = 0.84).
ANCOVA confirmed no group difference in fatigue: F(1,87) = 0.50, p = 0.483.
Baseline fatigue was a significant covariate in the ANCOVA model (R² = 0.27, η² = 0.006).
Effect size was small (Cohen's d ≤ 0.28).
Results
There were no statistically significant between-group differences in peripheral oxygen saturation after the intervention.
Mean difference in SpO₂ between groups: MD = 0.32 (95% CI: -0.15 to 0.80; p = 0.18).
Effect size was small (Cohen's d ≤ 0.28).
Both groups showed nearly identical SpO₂ gains (+0.40 vs. +0.42).
Methods
The study was a randomized triple-blind clinical trial conducted among adults with acute coronary syndrome in two Iranian hospitals.
92 adults with acute coronary syndrome were enrolled; 90 were randomized equally to intervention and control groups.
Participants were randomly assigned to Buteyko breathing (intervention) or diaphragmatic breathing (control) for six weeks alongside routine care.
Primary outcomes—sleep quality (PSQI), fatigue (MFI-20), and SpO₂—were measured at baseline and post-intervention.
Between- and within-group comparisons were performed using t-tests with effect-size estimation, and ANCOVA was conducted to adjust for baseline characteristics.
Results
Effect sizes for all between-group comparisons were uniformly small, indicating the observed differences were not clinically meaningful.
Cohen's d was ≤ 0.28 for all three outcomes (PSQI, MFI-20, SpO₂).
The authors concluded that changes were 'clinically insignificant with no between-group differences.'
The intervention cannot be recommended over standard evidence-based care based on these findings.
What This Means
This research suggests that a specialized breathing technique called Buteyko breathing does not provide additional benefits over standard diaphragmatic breathing for patients recovering from acute coronary syndrome (heart attacks or related conditions). The study enrolled 90 patients across two hospitals in Iran, randomly assigning them to either Buteyko breathing or diaphragmatic breathing exercises for six weeks, while both groups continued their usual medical care. All patients were evaluated for sleep quality, fatigue, and blood oxygen levels before and after the six-week period.
Both groups showed some improvement in all three measures over the study period, which likely reflects the benefit of regular breathing exercises in general, as well as ongoing medical treatment. However, when researchers directly compared the two groups at the end of the study, there were no meaningful differences between them—the Buteyko group did not fare better than the diaphragmatic breathing group on any outcome. The differences between groups were very small statistically and described by the authors as clinically insignificant.
This research suggests that while breathing exercises may offer some general benefit to heart patients—possibly by reducing stress, improving respiratory habits, or complementing medical care—the specific Buteyko method does not appear to be superior to simpler diaphragmatic breathing for improving sleep, reducing fatigue, or boosting oxygen levels. The authors concluded that Buteyko breathing cannot be recommended over standard evidence-based care based on these results, though both breathing approaches appeared safe and modestly helpful as add-ons to routine treatment.
Safarabadi M, Farsani S, Mohammadtalebi H, Kamani R, Mousivand M. (2026). Effects of the Buteyko breathing technique on sleep quality, fatigue, and oxygen saturation in patients with acute coronary syndrome: a randomized controlled trial.. BMC cardiovascular disorders. https://doi.org/10.1186/s12872-026-05635-w