Does cold water help with stress and low mood?

Cold water reliably lifts how people feel in the minutes after they get out, and that finding is real: in a randomised study of 64 undergraduates, a single immersion in 13.6°C sea water cut total mood disturbance from 51 to 36 on the Profile of Mood States, against a two-point change in the control group. What the research does not yet show is a lasting effect on stress, anxiety or depression. The largest pooled analysis, 11 randomised trials and 3,177 participants published in PLOS ONE in 2025, found stress significantly lower 12 hours after cold water immersion and no significant difference at 1, 24 or 48 hours. So: a well-measured short-term mood shift, an unproven long-term one, and some practical consequences for anyone choosing a plunge on that basis.

What does the research actually show about cold water and mood?

The best overview available is the 2025 systematic review and meta-analysis in PLOS ONE by Cain and colleagues, pooling 11 randomised controlled trials and 3,177 participants, with immersions at 7 to 15°C lasting 30 seconds to 2 hours at or above chest level. Its stress results are worth reading as a sequence rather than a headline, because the effect appears at one time point and nowhere else.

Time after immersion	Effect on stress (SMD)	95% confidence interval	Significant?
Immediately	−0.09	−0.45 to 0.63	No
1 hour	−0.29	−0.66 to 0.08	No
12 hours	−1.00	−1.40 to −0.61	Yes, p < 0.01
24 hours	−0.06	−0.50 to 0.38	No
48 hours	0.09	−0.28 to 0.46	No

A single significant time point sitting between four null ones is interesting rather than conclusive, and the review's own certainty rating for the stress outcome is Grade B. On mood specifically, the meta-analysis found no significant difference between cold water immersion and passive recovery, though that comparison rested on one study of 20 male participants, which is too thin to settle anything either way.

Two other findings from the same review deserve to travel with it. Inflammatory markers rose rather than fell immediately after immersion (SMD 1.03, 95% CI 0.37 to 1.68) and one hour after (SMD 1.26, 95% CI 0.59 to 1.94), which cuts against the common claim that cold plunging is anti-inflammatory. And in a separate long-term strand, cold showering was associated with a 29 per cent reduction in self-reported sickness absence.

Why do people feel so good straight afterwards?

Because the acute effect is the part with the clearest measurements behind it. Kelly and Bird, publishing in Lifestyle Medicine in 2022, put 42 undergraduates into 13.6°C sea water for around 19 minutes with 22 as controls, and measured mood before and after with the Profile of Mood States. Total mood disturbance fell 15 points in the immersion group and 2 points in the controls, with tension, anger, depression, fatigue and confusion all down and vigour and esteem-related affect up.

Yankouskaya and colleagues, in Biology in 2023, took 33 healthy adults aged 20 to 45 who had not cold-plunged in the previous 12 to 18 months, immersed them to the collarbones for five minutes at 19.93°C, and scanned them. Positive affect rose significantly (p < 0.001) and negative affect fell (p = 0.005), alongside increased coupling between the brain's default mode, salience and frontoparietal networks. The authors had no control group and call for replication.

Note the temperatures in both of those studies: 13.6°C and 19.9°C. The two experiments that measured mood most directly used water considerably warmer than the 3°C figure that dominates cold plunge marketing. There is no evidence at all that colder water produces a bigger mood effect, and nothing in the literature tests it below about 7°C.

Is there evidence for depression or anxiety specifically?

Not yet, and the clinical literature says so directly. A 2023 review in BJPsych Advances by Carona and Marques concluded that "the low methodological quality of the studies conducted so far (e.g. small, non-clinical samples; inconsistent water immersion protocols) precludes the extraction of clear conclusions", and that the study of cold water immersion's clinical applications "is still in its infancy".

The largest randomised trial in this whole field points the same way. Buijze and colleagues randomised 3,018 people in the Netherlands to finish their daily shower with 30, 60 or 90 seconds of cold water for 30 days. Sickness absence fell 29 per cent (incident rate ratio 0.71, p = 0.003), but work productivity and anxiety showed no significant difference, and the quality of life gain seen at 30 days had gone by 90 days.

For context on where that leaves cold water clinically: the NHS lists exercise, guided self-help, talking therapies such as CBT, and antidepressants as the treatments for depression, and says exercise "is one of the main treatments for mild depression". Cold water immersion appears on that list nowhere, because it has never been assessed at that level. That is a gap in the evidence rather than a verdict against it, but it is the accurate position today.

How much of the effect is the cold itself?

Less of it than the marketing implies, and this matters when you are deciding what to buy. Almost every study here carries at least one of four confounders: the immersion happens outdoors, it is a voluntary challenge people feel good for completing, it usually comes with a routine and often with company, and in the swimming literature it comes with exercise. Kelly and Bird designed their study to separate cold from exercise, which is why it is the most useful single result in this field, but they still measured young, fit students in the sea rather than a mixed population in a garden. The Yankouskaya authors name the same problem, listing "social or psychological factors" such as "courage to take the challenge" among the things their design cannot rule out.

When you should speak to a GP rather than buy a plunge

Low mood that lasts is a medical question, not a purchasing one. The NHS is specific: "A low mood often gets better after a few days or weeks", and "if you have a low mood that lasts 2 weeks or more, it could be a sign of depression". It advises seeing a GP if a low mood has lasted more than two weeks or if you are struggling to cope. If you are in crisis, urgent mental health support is available, and the Samaritans can be reached free on 116 123. No sauna or cold plunge is a treatment for any mental health condition, and nothing on this page should be read as one.

On the physical risks, three sourced points govern cold water for everyone:

• Heart conditions. The British Heart Foundation states that if you have a heart condition, "there are risks you should consider and discuss with your doctor or nurse specialist" before cold water activity, because cold shock raises heart rate and blood pressure and increases the risk of abnormal heart rhythms. Its stated safest range for people with heart conditions is 26 to 33°C, which is warmer than any cold plunge is built to reach.
• Technique, not duration, is what raises risk. Tipton's 2017 review in Experimental Physiology attributes immersion arrhythmias to autonomic conflict, triggered by simultaneous cold receptor and face-immersion responses, "particularly, but not necessarily, if a prolonged breath hold is involved". Enter slowly, stay seated, keep your face clear of the water, and never plunge alone.
• The first minute is the hard one. The RNLI notes that cold water shock causes an involuntary gasp with breathing rate "sometimes increasing as much as tenfold", and that "the initial effects of cold water pass in less than a minute".

If you take medication for a mental health condition, or have any heart or circulatory diagnosis, speak to your GP before starting regular cold water immersion.

What this means when choosing a cold plunge

If mood rather than athletic recovery is your reason for buying, the evidence points at a specific and slightly unfashionable specification.

Decision	What the mood evidence supports
Temperature	The mood studies used 13.6°C and 19.9°C. Nothing supports going colder for mood, so a chiller earns its place by holding a chosen temperature through summer, not by reaching 3°C.
Session length	Effects were measured after 5 minutes and after 19 minutes. Both worked. Short is enough.
Siting	Outdoors is where every one of these studies happened, and daylight and fresh air are plausibly part of the effect. A plunge in a windowless garage removes them.
Frequency	The acute lift is per session, so what matters is a tub you will actually use several times a week: step-in height, a lid you can move one-handed, and a short walk from the back door.
Running cost	Sessions are minutes; the chiller's standby hours are the cost. See the running cost arithmetic in full.

There is also a fair test worth running before you spend anything. The largest trial in this field used a 30 to 90 second cold shower, which costs nothing, and if a month of that does nothing for you, a tub is a large purchase resting on a hope. If it does, you will know what temperature and duration suit you before you choose equipment, which is a better position to buy from than most people manage.

Our guides on what temperature a cold plunge should be and how long to stay in set out the dose evidence in full, the muscle soreness research covers the recovery case, and what a cold plunge costs to run shows the arithmetic. When you are ready to look at hardware, the cold plunge range and Plan your space deal with the practical side.

Sources

• Cain T, Brinsley J, Bennett H, Nelson M, Maher C, Singh B. Effects of cold-water immersion on health and wellbeing: a systematic review and meta-analysis. PLOS ONE, 2025;20(1):e0317615.
• Kelly JS, Bird EL. Improved mood following a single immersion in cold water. Lifestyle Medicine, 2022;3(1).
• Yankouskaya A, Williamson R, Stacey C, Totman JJ, Massey H. Short-term head-out whole-body cold-water immersion facilitates positive affect and increases interaction between large-scale brain networks. Biology, 2023;12(2):211.
• Carona C, Marques S. Beyond the cold baths: contemporary applications of cold-water immersion in the treatment of clinical depression and anxiety. BJPsych Advances, 2023.
• Buijze GA, Sierevelt IN, van der Heijden BCJM, Dijkgraaf MG, Frings-Dresen MHW. The effect of cold showering on health and work: a randomized controlled trial. PLOS ONE, 2016;11(9):e0161749.
• NHS. Low mood, sadness and depression and Treatment for depression in adults.
• British Heart Foundation. Cold water swimming.
• Tipton MJ, Collier N, Massey H, Corbett J, Harper M. Cold water immersion: kill or cure? Experimental Physiology, 2017.
• RNLI. Cold water shock.