COLD PLUNGES, ANXIETY & DOING HARD THINGS ON PURPOSE

A gentle note before we go on: this piece touches on suicide and mental health.

A couple of weeks ago, 150+ people gathered on Eastern Beach at 6.15am on a Friday morning to do a cold plunge with I Am Hope.

There was that nervous, buzzy energy you get when a whole group of people are about to do something that feels a little scary. People standing at the edge of the water, psyching themselves up, people nervously giggling, people visibly thinking, absolutely not… and then, all of these humans walking into the ocean anyway.

But it was never just a cold plunge.

We were there with I Am Hope in support of mental-health awareness and suicide prevention, a cause that matters deeply to me. Heartbreakingly, I have been to enough funerals to know that we need to be having bigger, more honest conversations about mental health, especially in New Zealand.

New Zealand still loses around 600 people each year to suspected suicide. Our suicide rate also remains above the OECD average. Behind every one of those numbers is a whole person who was loved, and an entire circle of people left trying to make sense of a loss that never should have happened.

Standing on that beach with 150+ other people felt meaningful. It felt powerful because so many people had chosen to show up for a conversation that matters, to support an organisation doing important work and to be part of something bigger than themselves.

Whether it was I Am Hope’s intention or not, the cold plunge itself became such a beautiful metaphor for mental health.

You stand at the edge, everything in you wants to stay where it is warm and familiar. You take the first step, your breath gets taken away and your brain tells you to run, but then you stay, you breathe, you realise you can handle more than you thought you could and you come out the other side feeling stronger, clearer and a little more capable.

This is why I am such a strong believer in bringing awareness to tools and things that can support our mental health, including cold plunges.

Cold is a stressor… but in a good way (hear me out)!

This is where the hormesis part comes in.

Hormesis is basically a small, controlled dose of stress that your body can adapt to. Exercise is hormetic stress, sauna is hormetic stress, fasting can be hormetic stress and cold exposure is too.

The important distinction here is that the stress is controlled. From a nervous-system perspective, we want it to sit just on the edge of your window of tolerance.

Your body goes into a stress response when you get into cold water. Your heart rate rises, your breathing changes, blood vessels constrict and your nervous system very quickly goes, “excuse me, what are we doing?”

Without your breath and your focus, your body and mind can start to freak out. When you stay with it, regulate your breathing and let the first wave pass, you give yourself a powerful experience of: this was hard, but I was okay.

I think that is the part people miss.

Cold exposure has become a way for me to build evidence in my body that discomfort does not automatically mean danger. This is what I mean when I talk about getting comfortable in the uncomfortable. It is a constant reminder that I can do hard things, and a beautiful way to build resilience.

Why it can feel so good afterwards

There is a reason so many people get out of a cold plunge looking slightly unhinged but also absolutely buzzing.

Cold exposure activates the sympathetic nervous system and increases catecholamines, including noradrenaline. This is one reason you can feel alert, awake and switched on afterwards.

You will often hear the claim that cold plunges increase dopamine by 250%. That number did come from a real study, but it needs context. The study involved young men sitting neck-deep in 14°C water for one hour, and it measured dopamine in blood plasma, not dopamine in the brain after your two-minute morning shower (PMID: 10751106).

Cold exposure clearly creates an arousing effect in the body, and small experimental studies have found improvements in positive affect after short whole-body cold-water immersion (PMID: 36829490). If you have ever walked out of a plunge feeling brighter, more awake and oddly proud of yourself, your body is responding to the incredible thing you just did.

There is also something very grounding about putting yourself in these kinds of situations.

You cannot be halfway through a cold plunge and simultaneously overthink the email you sent three days ago, whether you remembered to reply to someone, your to-do list, or all the ways life feels overwhelming. The cold pulls you right into your body and right into the present moment.

What the research actually says about anxiety

The research around this is actually really interesting. A 2025 systematic review of 11 randomised trials, including more than 3,000 adults, found that cold-water immersion reduced stress twelve hours later. The same review also found improvements in sleep quality and quality of life across the studies included (PMID: 39879231).

In another three-week randomised study, 84 women with high stress and depressive symptoms practised either a daily hormetic-stress protocol that included cold showers and breathwork, or slow breathing with warm showers. Across the intervention, anxiety symptoms reduced by 27%, depressive symptoms by 24% and perceived stress by 20%, with those shifts still there three months later. The women doing the cold-shower practice also reported less rumination after stressful events, which is huge if you are someone whose brain likes to replay every conversation you have had since 2007 (PMID: 39606690).

Then there is the lived-experience side of this too. A recent study comparing 732 regular polar plungers with 501 non-plungers found the plungers reported better overall mental health. The sweet spot appeared to be around twice a week, which was associated with the lowest depressive-symptom scores in that group (PMID: 41127868).

It makes sense when you think about it. Cold water creates a big, immediate shift in your state. It wakes you up, pulls you out of the fifteen tabs open in your brain and into your actual body, and asks you to focus on the one thing in front of you: your breath.

The mental-health research on cold exposure is growing quickly now, looking across cold showers, plunges and winter swimming for stress, anxiety, mood and wellbeing outcomes (PMID: 42819812). I am paying attention.

I cold shower daily, except around my bleed, because it is this beautiful reminder that I can do hard things. It helps me build resilience and capacity for stress in a way I can honestly say has been life-changing.

How I use cold exposure as a woman

You have probably heard very differing advice when it comes to cold plunging or showering as a woman, and I think context matters.

Your cycle, sleep, energy availability, recovery, stress load and overall capacity all matter. The same stressor can land very differently when you are well-fed, recovered and feeling resourced versus when you are underslept, under-eating, in a high-stress season or already feeling completely wired.

There are days I love a genuinely cold shower or plunge. On other days, it feels harder, but I can still meet the edge of my comfort zone with 30–60 seconds. I am not pushing through or trying to win an award for suffering; I am using a small, intentional dose of stress to change the way I feel in my body and mind.

The week prior to and during my bleed is when I personally take a break from cold exposure and focus more on warmth, nourishment and supporting blood flow instead.

It is also worth noting that women’s lived experience is incredibly interesting here. In a survey of 1,114 regular cold-water swimmers, 46.7% reported less anxiety around their periods, while 46.9% of women in perimenopause reported an improvement in anxiety too. The women repeatedly described the water as calming, mood-boosting and grounding, alongside the companionship and community they found through swimming (PMID: 38271095).

Read my full guide on cold plunging for women and cycle-aware cold exposure here.

If you want to try it

Start with 30 seconds at the end of your normal shower. Take deep belly breaths before you switch the water to cold, keep your breathing regulated as the temperature shifts, let your body adjust and build gradually if it feels good for you.

When the cold hits, your breathing wants to become short and panicky, and your brain starts telling you to get out. Your job becomes very simple: breathe. Slow it down, stay present and remind your body that you are safe, even while something feels intense. If you are planning to do an ice bath, this part is even more important.

The goal is to meet a little discomfort, breathe, come back to yourself and leave knowing you are capable of more than you think. Sometimes, when life feels loud and your mind is spinning, you do not need another thing to overthink.

Sometimes you need to get out of your head and back into your body.

For me, cold plunging has become one piece of my mental-health toolkit. It is a way of practising presence when my brain feels busy, building trust with my body and remembering that I can feel discomfort and stay with myself.

That is what I want this month’s mental-health conversation to be about.

We need the big conversations. We need better access to support, we need to check in on the people we love, we need to keep talking about suicide prevention and we need to take mental health seriously long before someone reaches crisis point.

Part of that means knowing what helps us come back to ourselves in the everyday moments.

For some people, that is therapy. For others, it is medication, a walk outside, calling a friend, strength training, dancing, nourishing their body properly, getting into the ocean at 6.15am with 150 strangers, or finally asking for help.

Cold plunging may not be everyone’s thing. It does not need to be. I love that it gives us a very tangible reminder: we are capable of moving through hard moments, we can learn to breathe when our body feels activated, and we do not have to do any of it alone.

That morning at Eastern Beach, I watched a whole lot of people choose to do something hard together for a cause that matters. I think that is a pretty beautiful place to start.

Yours in Health & Happiness,
Sheree

A little note, just in case

If anything in this piece has brought something up for you, please do not carry it alone, tell someone, text a friend, call a loved one, reach out to someone you trust, even if you do not know exactly what to say.

If you are in NZ and need someone to talk to, you can call or text 1737 any time, day or night, for free, confidential support from a trained counsellor.

If you or someone you love is in immediate danger, please call 111.

You matter. Your life matters. The hard moment you are in does not have to be carried by you alone.

References

• Šrámek, P., Šimečková, M., Janský, L., Šavlíková, J., & Vybiral, S. (2000). Human physiological responses to immersion into water of different temperatures. European Journal of Applied Physiology, 81(5), 436–442. PMID: 10751106.
• Kelly, J. S., & Bird, E. (2022). Short-term head-out whole-body cold-water immersion facilitates positive affect and increases interaction between large-scale brain networks. Brain Sciences, 12(12), 1671. PMID: 36829490.
• Cain, T., Brinsley, J., Bennett, H., et al. (2025). Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis. PLOS One, 20(1), e0317615. PMID: 39879231.
• Blades, R., Mendes, W. B., Don, B. P., et al. (2024). A randomized controlled clinical trial of a Wim Hof Method intervention in women with high depressive symptoms. Comprehensive Psychoneuroendocrinology, 20, 100272. PMID: 39606690.
• Czarnecki, J., & Mokros, Ł. (2025). Inverted “u-shaped” association of cold-water immersion frequency with mental health and upper respiratory tract infection: A cross-sectional study. Brain, Behavior, & Immunity – Health, 49, 101118. PMID: 41127868.
• Pound, M., Massey, H., Roseneil, S., et al. (2024). How do women feel cold water swimming affects their menstrual and perimenopausal symptoms? Post Reproductive Health, 30(1), 11–27. PMID: 38271095.
• Ngandeu Schepanski, S., Batta, F., Schröter, M., Seifert, G., & Koch, A. K. (2026). Cold-water exposure and psychological outcomes in adults: A systematic review and meta-analysis. Frontiers in Physiology. PMID: 42819812.
• Tipton, M. J., et al. (2024). Habituation of the cold shock response: A systematic review and meta-analysis. Neuroscience & Biobehavioral Reviews. PMID: 38211547.