1. Increases dopamine anywhere between 2.5 to 400% and sustains it for approximately 2.5hrs, thus increasing motivation and drive. 
    
2. Raises the release of epinephrine (adrenaline) and neuroepinephrine (neurodrenaline), increasing focus, and desire/ability to move while also acting as a pain suppressant.
    
3. Improved Perceptual Speed, Visual Attentional Control, Working Memory (ability to remember information) and Energy.
    
4. Reduces stress, while improving mood and hormonal output.
    
5. Fortifies mental resilience and willpower.
    
6. Helps train our ability to stay calm during fight-or-flight response.

1. Promotes Circulations.
    
2. Increases Metabolism.
    
3. Helps convert white fat cells (often the less desired bluberry fat where energy is stored) into brown fat (thermogenic fat which can increase your body's natural temperature and metabolism).
    
4. Reduces abdominal fat.
    
5. Reduces inflammation in general, especially post-exercise.
    
6. Causes vasoconstriction — the tightening of blood vessels — which helps to push out lactic acid.
    
7. Enhances the physiological ability to withhold cold temperatures.
    
8. Can enhance strength and endurance training results.

BUDS candidates know uncomfortably cold water more than most. Typically, the water temperatures in San Diego reach a high of 69°F and drop into the low 50's during the winter. In their training, SEAL candidates have developed a method of postponing hypothermia by shutting down their shivering response. Nevertheless, their body temperatures still drop, allowing them to achieve the benefits of hypothermia: a slower metabolism and lowered oxygen requirements which extends their dive time.

Often less discussed is our body's temperature fluctuation associated with our circadian rhythm. Roughly, your core temperature is at it's lowest approximately 2hrs prior to waking up. Your temperature then continues to rise, peaking at it's highest temperature in the mid to late afternoon. 
 

It is valuable to keep this in mind for when you choose to use cold therapy — early mornings and late evenings will offer a more difficult mental and physical challenge.

Typically, following the first 15-30sec "shock period", you will calm down. I would recommend you occasionally stay in past that next "wall" period, which often comes between 2-4min after the initial submersion. As your body thermo-regulates, these walls will intermittently come and go, continuously challenging your mental fortitude.
 

PRO TIP: Instead of setting yourself timed goals, try setting yourself a set number of "walls" to overcome prior to starting every session.

Eg: One day you might just want to submerge and overcome that first "shock wall" in extremely cold water, while other days you might set yourself the goal of overcoming 2 walls of challenge within slightly less cold temperatures.

Few peer reviewed studies cover this topic, though some mention 11min total per week divided into 2-4 sessions of 2-3min.

Here are the most common/accessible types of cold therapy in order of most effective to least:

1. Cold Water Submergion: 2-10min up to the neck with hands and feet also submerged.
2. Cold Showers: >1min.
3. Cold Environment Exposure: >3min outside with minimal clothing.

Note: Cold water submersion creates > 4 times more heat transfer than cold air.

Uncomfortably cold to the point where you want to quit but you can safely keep going.

What should your mental state be? You basically have 2 options:

1. You can try to calm yourself.
2. You can grind it out.

NOTE: Challenging your pre-frontal cortex by doing math problems or trying to remember specific quotes/songs are valuable methods of training your brain to think while under tremendous stress (a crucial tool for any elite military professional).

If one stays still, the body expels heat thus creating a thermal layer around the body (kind of like a wetsuit). Movement breaks that thermal layer. So if you'd like to experience much colder temperatures and challenge your resilience even further; movement and/or river plunges can be, a fun variable to play with.

NOTE: If ever lost at sea, one can prolong their survivability in cold water by raising their legs and creating a bubble of warmer water. This same method can be used when in a group, by having everyone tread side-by-side in a circle with their feet raised and pointing inwardly.

For the purposes of elite military personnel, it may not be practical to practice the 10-15min Wim Hoff breath cycle prior to cold immersion as this does not mimic real world circumstances encountered in the field. For that reason, the most important breathing technique I personally recommend is simple: A LONG EXHALE.

Though challenging at times, implementing a long exhale when first entering the cold water has a surprisingly soothing/grounding effect on the mind. Aside from the fact that our heart rates slow during exhales, I find that inhaling feels very labored (almost like an asthmatic feeling) when one first enters the water. This can have the effect of inducing a feeling of panic.

The exhale, on the other hand, creates a calming effect. I've therefore concluded that the common saying "Take a deep breath in" when undergoing the traumatic stresses of life is false, rather than the more fitting phrase: "Release a long exhale".

Nevertheless, if time permits, trying the Wim Hoff breathing method can be a worthwhile experiment. Here's how to do it:

1. Get in a comfortable position;
    
2. Take a long inhale breath through the nose (fully inflating the stomach then the chest);
    
3. Exhale and exhale unforced through the mouth (this often results in what appears to be a quick exhale);
    
4. Repeat these breaths 30 to 40 times in short, powerful bursts (you may experience light-headedness, and tingling sensations in your fingers and feet. These side effects are completely harmles);
    
5. After the last inhalation, let the air out and stop breathing. Hold until you feel the urge to breathe again;
    
6. Repeat this cycle (step 1 through 5) 3-4 times.
    
7. Once completed, take your time to bask in the bliss. This calm state is highly conducive to meditation — don't hesitate to combine the two.

Some of the benefits associated with this breathing exercises include:

• Increased concentration and focus;
• Improved sleep quality;
• Increased energy levels;
• Reduced stress and anxiety;
• Enhanced physical performance;
• Boosted immune system.

WARNING: DO NOT combine the Wim Hoff breathing method with underwater breath holding exercises. Wim Hoff's breathing cycle induces hyperventilation which purges out CO2 (the body's natural mechanism that reminds us to breath). Combining Wim Hoff's method with apnea drills can very easily cause shallow water blackouts. We've dedicated an entire chapter of the Hold your Breath like a Helicopter Rescue Swimmer course to that exact topic.