Cold water therapy, like using the cold plunge tubs we have here at Capitol Floats, can have powerful effects on your hormones and overall health.
In a study called "Prolonged whole body immersion in cold water: hormonal and metabolic changes" researchers Smith, Deuster, Ryan, and Doubt wanted to see how the body’s hormones and metabolism react during long periods of being in cold water. They studied 16 divers who did four immersions in very cold water (about 41°F or 5°C) while wearing dry suits. These immersions happened twice a day—once in the morning and once at night—over five days.
Here’s what they found:
Stress Hormones (Cortisol and ACTH): These hormones, which are related to stress, showed a noticeable increase after the divers finished their night-time immersions. The body seemed to react more strongly to the cold at night.
Norepinephrine (NE): This is a hormone and neurotransmitter involved in the fight-or-flight response. After being in the cold water, the levels of norepinephrine increased more than three times. This increase was closely related to how much the body’s core temperature dropped.
Other Hormones: There were also increases in other hormones like triiodothyronine (T3) uptake and epinephrine (another stress-related hormone), but no changes in some other hormones like thyroxine (T4) and dopamine.
Metabolic Changes: The cold water caused a significant rise in free fatty acids (fats in the blood), which went up by over 400%. Blood sugar levels dropped, and lactate (a byproduct of intense exercise) increased.
In short, when people are in cold water for a long time, even with some protection like a dry suit and occasional exercise, their bodies still go through significant stress and metabolic changes, similar to what happens during shorter periods without protection. The body’s reaction to the cold is quite strong, especially at night, and involves big shifts in stress hormones and how the body uses energy.
Other Effects of Cold Water on Hormones
Cold water immersion has some pretty interesting effects on your body’s hormones. Here’s a breakdown of what happens:
Endorphins: When you take a dip in cold water, it numbs the nerves around your muscles and joints. This triggers the release of endorphins, which are your body’s natural painkillers. Not only do they help relieve pain and reduce inflammation, but they also give your mood a nice boost and make you feel good overall.
Dopamine: A cold plunge can cause a big spike in dopamine levels. Dopamine is the "feel-good" hormone, so this increase can leave you feeling happy, motivated, and alert. Czech researchers discovered that taking a cold plunge can boost dopamine levels by up to 250%.
Noradrenaline: Cold exposure boosts norepinephrine, a neurotransmitter linked to focus, mood, and alertness. This increase can lead to feelings of calm and happiness, helping to ease symptoms of depression and anxiety. This hormone is great for managing stress, giving you more energy and focus, and increasing blood flow to your brain. It’s also a key player in your body’s "fight-or-flight" response, helping you stay sharp in challenging situations.
Brown Adipose Tissue: Cold water immersion can also increase your body’s brown adipose tissue, which is a type of fat that’s really good at burning calories—even while you sleep! This is especially beneficial for women with PCOS, who often have lower levels of this metabolically active fat compared to other women. By increasing brown fat, cold immersion might help rebalance hormones in those with PCOS.
One research study showed that when people were exposed to cooler temperatures (around 16–19°C or 61–66°F) instead of a typical room temperature (24°C or 75°F), their energy expenditure—or the number of calories they burned—increased significantly. The volume and activity of their brown fat also went up, meaning this type of fat was more active in burning calories. Additionally, there was an increase in the intake of non-esterified fatty acids (NEFA) by the brown fat, which is part of the fat-burning process.
So, taking a cold plunge doesn’t just wake you up—it also triggers a range of hormonal changes that can improve your mood, boost your energy, and even help you burn more calories!
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