All four stress-reduction interventions—mindfulness meditation, slow breathing with warm showers, fast-paced breathing with cold showers (the Wim Hof Method), and high-intensity interval training—reduced depressive symptoms by about 16% and perceived stress by about 10% after three weeks in women with high stress. No group outperformed the others immediately after the intervention. However, a post hoc analysis of participants who adhered to their assigned program suggested that the Wim Hof Method group maintained lower depression scores and greater daily positive affect three months later, a finding that requires replication with larger, more diverse samples.
A three-week intervention comparing the Wim Hof Method (breathing technique inducing intermittent hypoxia plus cold showers) with slow-paced breathing and warm showers in 84 midlife women with high stress and depressive symptoms produced equivalent mental health improvements. Both groups showed a 24% reduction in depressive symptoms, a 27% reduction in anxiety symptoms, and a 20% reduction in perceived stress immediately after the intervention, with gains maintained at three months, when 46% reported mild or no depressive symptoms. Both conditions also reduced daily negative affect and peak cortisol reactivity to a laboratory stressor. However, the Wim Hof Method led to greater reductions in rumination after daily stressful events, a finding needing replication.