Cold Exposure for Women

Last Tuesday, one of our regular guests stood at the edge of our cold plunge for a full thirty seconds before stepping in. She wasn't building up courage; she had done this dozens of times before. She was hesitating because of something she had seen on Instagram.

"My friend sent me this thing," she said. "About how cold plunges mess with women's hormones. Is that true?"

We have heard some version of this question more than a dozen times in the last month, always referencing something they saw on social media, and felt it was time to offer perspective on women's approach to cold exposure.

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Where the fear came from

In 2025, a study was published showing that cold water immersion disrupted hormonal cycles in female mice. The protocol was 39°F water, six minutes per day, for twenty-one consecutive days, with no rewarming. The researchers found elevated estrogen, FSH, LH, and inflammatory markers in reproductive tissue.

Then the internet did its thing.

Dr. Stacy Sims, an exercise physiologist with a PhD from the University of Otago and a postdoc at Stanford, went on the Mel Robbins podcast to talk about it. Her actual position was nuanced. She recommended that women use slightly warmer water, around 59°F instead of 39°F, to avoid excessive cortisol stress. That is a reasonable suggestion with a real basis in physiology.

Podcast clips don't carry nuance, though. The sound bite that ended up traveling was: ice baths are bad for women.

A host of others chimed in. An acupuncturist named Katie Pedrick posted a video saying cold plunges aren't great for women, and that also went viral.

Sims later clarified: "I didn't say women shouldn't cold plunge." By that point the clip was already doing what clips do.

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The study nobody actually read

Let's go back to those mice.

The protocol was 39°F water, six minutes every day, twenty-one days in a row, no sauna, no rest, no recovery of any kind in between sessions. That is 126 total minutes of sustained cold stress on an animal that weighs less than your phone.

A session at Elahni is three minutes of total cold exposure, split across three rounds, with a 180°F Finnish sauna between each one. Your core temperature recovers completely before the next round begins.

That is 42 times less cold exposure, with full thermal recovery, on a human being.

The mouse study itself is real science. Extrapolating from that protocol to "your monthly cold plunge is hurting your hormones" is not.

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What happens when you study actual women

In 2024, a peer-reviewed study surveyed 1,114 actual women who regularly swim in cold water.

• 56% reported their menstrual symptoms improved.
• 47% reported reduced anxiety.
• 30% of perimenopausal women reported relief from hot flashes.

The women in the study also reported that colder water produced greater positive effects, not less of them. 1,114 women is a meaningful sample, and a ratio of 56 to 1 between those who felt better and those who felt worse is hard to dismiss.

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The cortisol question

The biggest fear is that cold water spikes cortisol and puts the body under chronic stress.

In 2000, researchers measured hormone responses to cold water immersion at three different temperatures. At 57°F, cortisol tended to decrease. At 68°F, the same. What did spike was norepinephrine, by 530%, and dopamine, by 250%. Those are not stress molecules. They are most of what makes you feel focused and awake and capable of handling whatever your inbox has been holding.

The full picture is a little more complicated than "cortisol drops." If you are brand new to cold water, your first few sessions will probably produce an acute cortisol spike. The body perceives the temperature as a threat and responds accordingly. That is normal.

With regular practice, though, something shifts: your baseline cortisol lowers, and your nervous system learns that the cold is not actually a crisis. Researchers call this cross-stressor adaptation. The short version is that you get better at handling all stress, not just cold water.

The clarity you feel after a session is not a placebo, it is norepinephrine and dopamine doing exactly what they are designed to do.

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The gender question, turned upside down

"Women shouldn't do what men do in the cold."

We hear this one a lot. It sounds progressive and respectful of biological difference. The problem is that the research underneath it was conducted almost entirely on men. The 2025 systematic review of cold water immersion included 11 randomized controlled trials and 3,177 participants, and only one of those studies included women. The conclusions about female physiology are being extrapolated from male data.

When researchers have actually tested both genders, the findings have been surprising. In several measures, women may have an advantage.

Women carry larger and more active brown fat deposits than men, an evolutionary adaptation for having less muscle mass. Cold exposure activates these deposits and improves insulin sensitivity and metabolic rate. One landmark study showed that just 10 days of mild cold acclimation at 59°F increased insulin sensitivity by 43% in patients with type 2 diabetes.

Women also vasoconstrict faster than men. That sounds like a problem, but it is actually a protective mechanism: blood gets shunted toward the core to preserve organ temperature. Women defend their core temperature with equal or greater efficiency than men do, using blood-flow regulation instead of shivering.

Dr. Susanna Soeberg's research on cold-induced thermogenesis, the Soeberg Principle of ending on cold to maximize the metabolic afterburn, looks highly applicable to women. Because women have more brown fat, they may reach the metabolic threshold for benefit faster. Two to three minutes may be more efficient for women than five minutes is for men.

The data is not saying women should do less. It is saying women may need less of it to get the same benefit.

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Your cycle changes the experience, not the safety

This is one area where the nuance matters, and where Sims was pointing at something real even if the version that traveled got distorted. The menstrual cycle creates a fluctuating internal environment that does genuinely affect how cold feels.

1. Days 1-14 (follicular phase). Estrogen is the dominant hormone, your core temperature is lower, and your cold tolerance is higher. This is the window for the most intense sessions. The body handles cold well here, and the stress-resilience benefit is at its peak.
2. Around ovulation. Peak resilience. Some women find the cold actually helps with ovulatory discomfort.
3. Days 15-28 (luteal phase). Progesterone raises your core temperature by about half a degree, so the cold feels colder, sooner, and more intense than it did two weeks earlier. If there was a phase to moderate your cold exposure use, it would be here.
4. During your period. It varies. Some women feel great in the cold, others want nothing to do with it, and both are valid. Focus on heat, and if the cold calls you, keep it short.

None of this means cold is unsafe at any point in your cycle. It means your relationship to it shifts, which is true of almost everything your body does across a month.

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What we actually see

More than half of our regular guests at Elahni are women. That wasn't a strategic decision, it's just what happened.

We love getting messages from our community on the felt difference. Unprompted texts, days after a session:

• "I slept through the night for the first time in weeks."
• "I don't know what you did to me but my anxiety is way down."
• "My shoulders haven't been up by my ears since Tuesday."

Women book out the space privately more often than men do. Groups of three or four, catching up the way they would over dinner, except between rounds of 180 and 40 degrees. Conversations happen differently when your nervous systems have been through something together.

The breathing tends to come more naturally to women, too. There is something about how women settle into the exhale that experienced practitioners notice: less fighting, more listening to whatever signal the body is actually sending.

This is what we have seen across thousands of sessions. None of it lines up with "cold plunges are bad for women."

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What you should know before you go

• If you are trying to conceive: skip the cold plunge during the luteal phase. Progesterone raises your core temperature to support implantation, and aggressive cooling during that window could theoretically work against the process. The sauna is generally considered safe while trying to conceive, but it is usually discouraged once pregnancy is confirmed, particularly in the first trimester.
• If you have PCOS: early research suggests cold-induced brown fat activation may support metabolic health by improving glucose uptake and insulin sensitivity. The evidence is still primarily from rodent models, but the direction is promising.

For everyone else, the body already knows how to do this. The cold gives it a reason to remember.

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The actual conflict

The social media narrative got the framing wrong. The conflict isn't really between cold water and women. It is between extreme, unsynchronized cold exposure and the female neuroendocrine system. A mouse submerged at 39°F for twenty-one consecutive days with no recovery is not the same thing as a woman stepping into a cold plunge for sixty seconds between rounds of a Finnish sauna.

Context is the entire story.

Moderate cold, paired with heat, loosely synced with the cycle, and practiced regularly, is not just safe for women. The evidence, across 45+ sources, suggests it might be one of the places where some of the deepest benefits actually live.

The body told you this before the research did. The research is just catching up to it.

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Based on 45+ peer-reviewed sources including PMC systematic reviews, PubMed controlled studies, and Finnish population-level epidemiological data spanning 26 years.