When it comes to cold plunging, there’s a counterintuitive technique that separates novices from experts: experienced practitioners submerge their faces immediately upon entry. During a recent episode of The Joe Rogan Experience, neuroscientist Dr. Andrew Huberman explained the fascinating physiological reason behind this practice, revealing why this approach is far more than just a display of mental toughness.
Huberman, a professor of neurobiology at Stanford University, shared insights from his conversation with Dr. Susanna Søberg, the Danish researcher who created the “Søberg Principle” for cold exposure. According to Huberman, the key lies in activating what’s known as the mammalian dive reflex.
“When you put your face in the water right as you go in, you activate the mammalian dive reflex,” Huberman explained to Rogan. This reflex triggers a cascade of physiological responses, most importantly increasing parasympathetic nervous system activity. In simpler terms, it actually makes you calmer rather than more stressed.
The benefits are substantial and immediate. “It lowers your heart rate, it makes you calmer, and it makes you better able to tolerate stress,” Huberman noted. This is the exact opposite of what many people experience when they slowly ease into cold water, keeping their head above the surface while their body adjusts to the temperature shock.
The common approach of gradual immersion, slowly lowering yourself into the water up to your neck, can actually make the experience more difficult and potentially problematic. Huberman pointed out that this creates a problematic temperature gradient at the waterline.
“A lot of people that do deliberate cold get headaches, they don’t feel good, and a lot of times it’s because they slowly immerse themselves up to the neck,” he explained. This interface between cold water and warm air causes vasoconstriction below the waterline and vasodilation above, which can trigger headaches and overall discomfort.
The immediate face submersion technique bypasses these issues entirely. By activating the mammalian dive reflex from the outset, practitioners essentially hack their nervous system to work with them rather than against them.
The body interprets the facial cold water contact as a signal to enter “dive mode,” automatically slowing the heart rate and increasing oxygen efficiency, responses that evolved to help mammals survive underwater.
During the conversation, Rogan acknowledged his own practice of immediate submersion, noting the psychological battle that occurs in those first moments. “There’s a moment when you get in the cold where there’s a part of your brain that goes, ‘let’s get the hell out of here, you can get out of this if you will just get out right now,'” he described.
Huberman emphasized that the first 20 to 30 seconds of cold exposure represent a critical window. During this time, the prefrontal cortex, the part of the brain responsible for rational decision-making and impulse control, temporarily goes offline.
“Your reflex to get the hell out of there is very clear and there’s a logical reason for that,” he explained. After this initial period, the forebrain starts coming back online, allowing for negotiation with oneself about staying in the water.
The conversation also touched on the broader benefits of cold exposure, which Huberman has researched extensively. Referencing Søberg’s work, he noted that just 11 minutes of deliberate cold exposure per week, divided into sessions of one to four minutes, can fundamentally change brown fat levels, increase mitochondrial function, and improve metabolism.
These benefits extend far beyond the immediate experience, with increases in dopamine, norepinephrine, and epinephrine lasting four to six hours after exposure.
