“Cold water treats depression and anxiety.”

The research found this

There is no completed, full-size randomized trial of cold-water immersion or cold showers as a treatment for diagnosed depression or anxiety. The closest randomized test enrolled 84 otherwise healthy midlife women in the US with high stress and high depressive symptoms.1Source 1 · Randomized trialA randomized controlled clinical trial of a Wim Hof Method intervention in women with high depressive symptomsBlades R, Mendes WB, Don BP, et al.. Comprehensive Psychoneuroendocrinology, 2024.Read the paper ↗PubMed ↗ For three weeks, one group did a daily 15-minute audio-guided session of Wim Hof-style breathing plus cold showers, and the other did slow breathing plus warm showers.

Both groups improved about equally. Depressive symptoms fell 24% and anxiety 27%, and the gains lasted to three months.1Source 1 · Randomized trialA randomized controlled clinical trial of a Wim Hof Method intervention in women with high depressive symptomsBlades R, Mendes WB, Don BP, et al.. Comprehensive Psychoneuroendocrinology, 2024.Read the paper ↗PubMed ↗ The researchers had registered a prediction that the Wim Hof group would do better, and the data did not support it. That group did brood less after daily stresses, and all six dropouts came from it.

In a 2025 UK trial, researchers randomly assigned 87 adults with mild to moderate depressive symptoms to an eight-session outdoor swimming course plus usual care, or to usual care alone.2Source 2 · Randomized trialOUTSIDE: OUTdoor Swimming as a nature-based Intervention for DEpression: a feasibility randomised controlled trialMassey H, Denton H, Burlingham A, et al.. Mental Health and Physical Activity, 2025.Read the paper ↗ Of the swimmers, 79% made it to at least four sessions, and the comparisons favored swimming with medium to large effects. This was a feasibility trial, built to test whether a full study could run, and it was too small to show whether swimming works.

The rest of the evidence is thinner. A 2018 case report described a 24-year-old woman whose depression had not responded to two antidepressants. After she took up weekly open-water swimming her symptoms eased gradually and she came off medication, and a year later she was still off it.3Source 3 · Case reportOpen water swimming as a treatment for major depressive disordervan Tulleken C, Tipton M, Massey H, et al.. BMJ Case Reports, 2018.Read the paper ↗PubMed ↗ A 2008 paper in Medical Hypotheses proposed two to three minutes of 20°C showers as a depression treatment and reported no trial.4Source 4 · Hypothesis paperAdapted cold shower as a potential treatment for depressionShevchuk NA. Medical Hypotheses, 2008.Read the paper ↗PubMed ↗

Other small trials point in different directions. In 62 people with spinal cord injury, adding cold to Wim Hof breathing made no difference to mental health scores, and in a four-group stress trial only breathing plus cold beat the control group.5Source 5 · Randomized trialThe effect of breathing exercises and mindset with or without cold exposure on mental and physical health in persons with a spinal cord injury—Results of a randomized controlled trialde Groot S, Ettema FW, van der Bijll M, et al.. Clinical Rehabilitation, 2026.Read the paper ↗PubMed ↗6Source 6 · Randomized trialThe positive effects of combined breathing techniques and cold exposure on perceived stress: a randomised trialKopplin CS, Rosenthal L. Current Psychology, 2023.Read the paper ↗PubMed ↗ A 2026 review in Molecular Psychiatry called cold exposure promising and still unproven for mood, and it pointed to small studies and missing placebo controls.7Source 7 · ReviewIs cold exposure a viable lifestyle intervention for mental health? Reviewing evidence and mechanismsBrowning L, Fabiano N, Luu B, et al.. Molecular Psychiatry, 2026.Read the paper ↗PubMed ↗