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Written by Daniel Z. Lieberman, MD
Quick! What do Hailey Bieber and David Beckham have in common?
Stumped? The answer is cold plunging, the trend that’s been steadily sweeping social media. These celebrities, and many more like them, have posted videos in which they’re lowering themselves into tubs of frigid (and in some cases, ice-filled) water.
Bieber says the ritual helps with her anxiety, and plenty of TikTokers have been touting the benefits of the practice. As of right now, #coldplunge has over 1.6 billion views on TikTok.
But can braving arctic temperatures really help with your mental health? Is it worth it to invest in a pricey plunge tub for your home, or membership to a spa that offers the service?
We checked in with Dr. Daniel Lieberman, Clinical Professor of Psychiatry and Behavioral Sciences at George Washington University and SVP of Mental Health at Hims and Hers, to ask whether dropping the temp can drop your anxiety, too—and learned something surprising right away.
Dr. Lieberman: So the first point I want to make is that the technique that may actually help with anxiety isn’t the same one celebrities and other people online are generally referring to when they talk about “cold plunges” at all. It’s really a face dunk.
The reason this is so important is that a face dunk and a cold plunge have opposite effects on the nervous system.
A face dunk is when you plunge just your face into ice-cold water. This stimulates something called the diving reflex. That's a reflex that all mammals have evolved in order to prepare our bodies physiologically for being underwater and not having access to oxygen.
The diving reflex stimulates a parasympathetic response, and that's a term that most people aren't familiar with. What's key to know is that one of the most important nerves in the body for a parasympathetic response is called the vagus nerve.
Vagus comes from a Latin word that means “to wander.” The nerve is called this because it wanders all over the body, making all different kinds of stops. And one of the places it stops is the heart. And when it's stimulated, the heart slows down.
We know that when your heart rate goes up, your anxiety can go up, as well. A rapid heart rate is often a response to some kind of threat that throws your body into fight or flight mode. But if you make your heart rate go down, anxiety can go down as well. Stimulating the diving reflex with a face dunk is one way to do it.
I was thinking about when I would use something like this. And I thought, Well, maybe before I go up and give a big important talk. In those instances, my heart rate definitely zooms up. I sweat, I maybe tremble a little bit. A bucket of ice water to dunk my face in would be really helpful at that point.
Interestingly, there are nerves inside the nostrils which seem to have the most potent effect on this diving reflex. So ideally, you want to get that cold water up into your nostrils, if possible, to get the greatest effect.
So that’s where we’re going to see the sympathetic response, which people are more familiar with. It’s commonly known as “fight or flight.”
That's when you get this surge of adrenaline and your heart rate goes up. You might start trembling, you might start sweating. That's how you feel, say, if you're going to give a big presentation and you're really nervous.
This is what a cold plunge does, too. It stimulates the same “fight or flight” response. So doing a full cold plunge doesn't really have a lot of mental health benefits. It's really more useful for athletes. It helps them repair their muscles after a very hard workout.
Yes, the most important thing to know about that is that they can be dangerous. The human body was not designed to be immersed in very, very cold water.
The recommended temperature is 50 to 70 degrees, so we're not talking about jumping in an ice bath here. That can cause a severe increase in heart rate, potentially even leading to heart attacks in people who have heart disease.
Even if you stay in a 70-degree bath for too long, you can get hypothermia. It's really quite dangerous, so if you want to try a cold plunge you shouldn't stay in for more than a few minutes.
Another way of stimulating your parasympathetic nervous system is with deep, slow breathing. And that's going to be more practical, in many cases, than plunging your face in cold water.
You can imagine if you're on a date, it might not exactly be ideal to run into the bathroom to try and splash cold water on your face. It might be easier to use some deep, slow breathing.
This doesn't give me any concern at all, unlike most social media trends. I think the most important thing to keep in mind is that it’s different from a cold plunge. Face dunking is very safe. It's a wonderful thing to try. And I have no concerns about people trying it on a periodic basis to lower situational anxiety.
The effect lasts for a few minutes, which is not very long, but I think it's still worth doing. If you can do something to make your anxiety go away in a given situation, even for a little bit, it can give you a feeling of control over that anxiety.
Simply being able to take that control, even when the physiological effect wears off, I think you're still going to feel a little bit more grounded, a little bit less anxious.
For people who really have a significant amount of problem with stage fright or being anxious on a date or a job interview or any other stressful social interaction, there are medications called beta-blockers.
And the most commonly known one is propranolol, which suppresses the fight or flight response. And that’s generally going to take care of things like rapid heart rate, trembling and sweating. Unlike a face dunk, the effects of the propranolol will last for hours.
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