Does Cold Water Swimming Improve Your Mood the Same Day?
Yes. This diary study found that regular cold water swimmers had significantly lower anxiety and higher self-confidence on days when they swam compared to days when they didn’t. These benefits even carried into the next morning with better sleep and lower anxiety.
Researchers used a twice-daily diary method to track 13 female cold water swimmers in the UK over a two-week period. This is the first study to capture the immediate, same-day effects of cold water swimming rather than measuring changes over months.
Dr. Kumar’s Take
This study is special because it captures what cold water swimmers actually experience day-to-day. Previous research looked at changes over months. This study shows that the benefits happen immediately. You swim, and that night your anxiety is lower and your self-confidence is higher. You wake up the next morning feeling better and having slept better. These daily improvements may explain why people keep coming back to cold water swimming.
Study Design
Researchers recruited healthy female swimmers who regularly swam in cold water at least twice per week. Participants completed questionnaires twice daily:
- Morning: Questions about sleep quality, wellness, and whether they swam the day before
- Evening: Questions about anxiety, self-confidence, and whether it was a swim day
The number of swim days ranged from 3 to 12 across the study period, with an average of 6.5 swim days.
Same-Day Effects
On days when participants swam, compared to non-swim days:
State anxiety: Significantly lower on swim day evenings (7.49 vs 10.19, p < 0.01)
Cognitive anxiety: (worry and self-doubt) Significantly lower (11.47 vs 14.10, p < 0.05)
Somatic anxiety: (physical tension) Significantly lower (9.86 vs 11.78, p < 0.05)
Self-confidence: Significantly higher (31.49 vs 26.50, p < 0.01)
All effects had large effect sizes, meaning the differences were meaningful, not just statistically significant.
Next-Day Effects
The morning after swimming, compared to mornings after non-swim days:
State anxiety: Significantly lower (9.32 vs 10.84)
Cognitive anxiety: Significantly lower (12.98 vs 14.62)
Somatic anxiety: Significantly lower (11.2 vs 12.8)
Morning wellness: Significantly higher (4.40 vs 3.79)
Sleep enjoyment: Significantly higher (4.19 vs 3.7)
Physical tension in bed: Significantly lower (1.33 vs 1.61)
Why Cold Water Swimming Works
The researchers suggest several mechanisms:
Vagal stimulation: Cold water activates the mammalian diving reflex, which slows heart rate and triggers the body’s relaxation response.
Neurotransmitter release: Cold water triggers release of dopamine, serotonin, and beta-endorphins, which increase feelings of happiness and contribute to the “post-swim high.”
Connection to nature: Being in natural water environments has psychological benefits beyond the cold itself.
Social support: Swimming with others provides community and reduces isolation.
Achievement: Facing the challenge of cold water builds self-confidence that carries into other areas of life.
Limitations
The study had a small sample (13 women) and relied on self-report measures. The participants were already regular swimmers, so results may not apply to beginners. The study couldn’t separate the effects of cold water from the effects of exercise and social connection.
Practical Takeaways
- Cold water swimming appears to reduce anxiety and improve self-confidence the same day
- Benefits extend into the following morning with better sleep and lower anxiety
- Regular practice (the swimmers averaged 5-6 swims per week) may amplify these benefits
- Daily improvements may contribute to longer-term mental health benefits
Related Studies and Research
- Related Podcast Episode
- Systematic review/meta-analysis: CWI and post-match recovery in soccer players
- Limitations of facial immersion as a test of parasympathetic function
- The experiences of open-water swimmers with depression (qualitative)
FAQs
How soon after swimming do the benefits appear?
This study measured benefits the same evening as swimming and the following morning. The improvements were present at both time points.
Do I need to swim multiple times per week?
The participants in this study swam an average of 5-6 times per week. While this study doesn’t test different frequencies, regular practice appears to be associated with consistent benefits.
Will these benefits work for people with diagnosed anxiety?
This study involved healthy participants without diagnosed mental health conditions. However, other research suggests potential benefits for people with anxiety and depression. Always consult your doctor before starting cold water swimming.
Bottom Line
This exploratory study is the first to use daily diary methods to capture the immediate effects of cold water swimming. Among 13 regular female swimmers in the UK, swimming days were associated with significantly lower anxiety and higher self-confidence compared to non-swim days. These benefits persisted into the next morning, with improved sleep quality and lower anxiety levels. The findings suggest that cold water swimming produces both immediate and next-day improvements in mental well-being. These daily benefits may explain why regular swimmers continue the practice and may underlie the longer-term mental health improvements seen in other studies.
