The Effect of Yoga Breathing Exercise on Stress and Sleep Quality in Women With Breast Cancer Undergoing Chemotherapy.

To evaluate the effect of yoga breathing exercise (YBE) on perceived stress and sleep quality in women with breast cancer undergoing chemotherapy. This randomized, sham-controlled trial was conducted in the chemotherapy unit of a university hospital in Türkiye from November 2023 to April 2024 and involved 60 women with stage II-III breast cancer undergoing chemotherapy. Participants were randomized to a YBE group or a sham breathing group. Both groups received standard oncology care, and the YBE group additionally practiced 4-4-4-4 yoga breathing twice daily for five minutes during 21 days. Data were collected at baseline and after the 21-day intervention period. Perceived stress and sleep quality were assessed using the Perceived Stress Scale and the Pittsburgh Sleep Quality Index. Data were analyzed using two-way repeated-measures analysis of variance. After 21 days, the YBE group showed significantly greater reductions in perceived stress (mean difference = -6.23, p < 0.001) and improved sleep quality (mean difference = -2.1, p < 0.001) compared with the sham group. No adverse events were reported. YBE can be integrated into supportive oncology nursing care as a low-cost, nonpharmacologic intervention to address stress and sleep disturbances during chemotherapy.