Hydrotherapy and Cold Water for Mood and Depression: What Studies Show and Claims Checked

If you are in crisis

If you are thinking about harming yourself or feel you may not be safe, call 988 in the United States, or call 911 for an emergency. Do not go into cold water, a hot tub or a bath alone while feeling this way. Depression is a medical condition. The NHS says severe depression can make you feel suicidal and that it is important to see a doctor [1]. Water practices are, at most, an add-on to care. Never stop or change a prescribed medicine because of anything you read here.

The short answer

Cold showers, cold-water swimming and cold plunges are widely promoted for mood. Reviews find the results promising in direction but not reliable: studies are small, many are not controlled, and most have a high risk of bias. A 2026 meta-analysis concluded the evidence does not establish that cold-water exposure improves mood or depressive symptoms and that it should not currently be regarded as a standalone treatment for psychiatric disorders [2]. Evidence label: insufficient evidence for depression; promising but limited for short-term wellbeing. For warm baths and hot tubs, Proper evidence not found (see below).

What the sources found

1. Does cold-water exposure improve mood and depression?

   Low; does not establish benefit

   A 2026 review of 13 studies (4,105 people) found pooled estimates generally favored cold-water exposure, but confidence intervals were wide, several estimates shrank in controlled-only analyses, and most studies had high to critical risk of bias [2]

2. What about anxiety?

   Low

   The same review found little evidence of consistent benefit for anxiety [2]

3. Healthy adults, randomized trials

   Low to moderate; few trials, small samples

   A 2025 review of 11 studies (3,177 people) of baths and showers at 7 to 15 degrees C found improvements in sleep quality and quality of life, but not mood. Stress fell 12 hours later but not at other time points [3]

4. People with depression

   Pilot; no control group

   A small open-label feasibility study: 13 patients recruited, 5 took part regularly in supervised cold-water swimming. Well-being and sleep scores improved in those five [4]

5. Cold showers in the general population

   Randomized; mood was not its main outcome

   In a trial of 3,018 adults, a (hot-to-) cold shower routine reduced self-reported sickness absence by 29%, with no group effect on illness days [5]

6. Women who swim in cold water

   Self-report; cannot show cause

   In an online survey of 1,114 regular swimmers, many said cold-water swimming eased menstrual and perimenopausal mood symptoms [6]

Why these studies are hard to trust

You cannot hide cold water from the person in it, so expectation can shape mood scores. Many studies were not randomized, followed people for a short time and measured mood right after the water, which is not the same as treating depression over weeks. People who choose winter swimming may differ from those who do not. The 2025 review also found an acute rise in inflammation markers immediately and an hour after cold-water immersion [3], a reminder that short-term body changes are not health outcomes. A cold dip also sits alongside company, nature and exercise, which may be part of any benefit; the survey authors noted companionship and community as a theme [6].

Proposed explanations, not established

Some popular accounts suggest cold exposure acts through stress hormones or brain chemistry. The abstracts we read did not test these ideas in people with depression, so we treat them as proposals only.

Warm baths, hot tubs and depression

Proper evidence not found. We searched PubMed for hot bath, hot water immersion, balneotherapy, spa and hot spring bathing with depressive symptoms and found no controlled trial we could read. For warm baths and relaxation more generally see warm baths: relaxation and sleep and hydrotherapy for stress and relaxation.

What the NHS says helps depression

The NHS describes talking therapies such as CBT, antidepressants for moderate to severe depression, and lifestyle measures such as exercise [1]. For stress, anxiety and burnout see our Wellness page on stress vs anxiety, burnout and depression.