The purpose of inflammation is to eliminate the initial cause of cell injury, clear out dead cells and tissues damaged from the original insult, and initiate tissue repair.

However, when it runs awry, in the absence of actual biological threat, we're in trouble. Inflammation has been identified as key driver of aging process, and is associated with most age­-related diseases.


Cold - what is it good for? Lots, we are discovering. Immune response, inflammation, fat burning, anti-oxidation,

Norepinephrine (vigilance, focus, attention and mood)↑

Cytokines (inflammatory markers) ↓

Good stress = “hormetic”; a short­-term stressor that has benefits

Prophylactically protective for TBI

Cold shock proteins such as RBM3 rebuild neurons

Norepinephrine, induced by cold, reduces inflammation by decreasing tumor necrosis factor alpha (TNF-alpha), implicated in almost every human disease from Type 2 diabetes to inflammatory bowel disease and cancer.

Cold appears to increase lymphocyte numbers. This is in line with the fact that habitual winter swimmers have higher number of white blood cells compared to non-­habitual winter swimmers.

Boosts metabolism (300% for 1 hr at 68 degrees)

Non­shivering thermogenesis (brown fat activation)-  responsible for the “fat burning” effect of cold exposure once the body has adapted to cold exposure.

Amount of brown fat is inversely correlated to percent body fat.

The greater the release of norepinephrine that we can induce from cold, the more brown fat produced.

Cold activates very potent genetic antioxidant systems which are exponentially more powerful than supplemental antioxidants (glutathione reductase, and superoxide dismutase).

Cold is a tool, so use it wisely. Muscle growth is an inflammatory process. So, if you are trying to build muscle mass, wait on the ice bath for at least an hour of after working out.

Even more esoteric: Cold exposure activates a gene called PGC­1α, which makes more mitochondria in the muscle. Mitochondria are your cell’s engines; they produce energy and heat. More mitochondria per muscle cell directly translates to aerobic capacity, and a single 15 minute exposure to cold water (50°F) following high intensity running, increases PGC­1α in muscle tissue.

So, re cold:

  • Trains thermogenesis

  • Brown fat raises insulin sensitivity, a critical health marker

  • The body will adapt to function; Give the body a reason to become good at something

  • BP drops; HR drops; circulation improves

  • After ice bath, sit in meditation; This is where you can choose to generate heat from brown fat vs shivering; Shivering is also a response to cold, but less controlled, less efficient

  • Trust that the body gives you what you need, then divert it to what you want

  • Safety: Afterdrop - Get out if shivering, erratic breathing; before you feel cold; Focus after exposure.

  • Increases norepinephrine  up to 5-fold in the brain.   Temperature and duration needed to do this is 40°F (4.4°C) for 20 seconds

  • Norepinephrine has an effect on mood, increases vigilance, focus, and attention (especially over a prolonged period).

  • Cold exposure increases cold shock proteins, including one in brain that repairs damaged synapses and in muscle prevents atrophy.

  • Cold-induced norepinephrine lowers inflammation and pain by decreasing levels of inflammatory mediators.

  • Chronic cold shock may increase immune cell numbers including a type of immune cell that kills cancer cells.   

  • Cold exposure increases metabolic rate, number of mitochondria, and burning of fat.  

Fear of Death

"Fear of death is the fear of not having fully lived."  I first heard this from Wim Hof, and it immediately made sense to me.   I have seen people close to me (my mother as my primary example) approach death with open eyes.  More commonly, I have seen people fearful and fighting it.  The few who died well were close to their families, happy, and relentlessly worked on their relationships and connections.  And they left no ghosts.  

Die Before You Die

Imagine you're dead.  You just died.  What has your life added up to?  What do you regret not doing or feeling or apologizing for?  What connections did you intend to make but never did?  How did you leave things with friends and family?  And what feels complete, well-done, whole?  

Take yourself all the way from right now to the end of your life.  Who are you at the end?  This is the most rigorous, honest appraisal of yourself you will make.  Repeat this exercise over and over, make it a habit of mind, until it is second nature.  Your priorities will remain aligned if you do.  

Memento Mori

Remember that you will die.  Carry a reminder to keep this ever present, to make the flavor of every moment more delicious.  Maybe a stone in your pocket, a tattoo, or some small adornment that you see every day.  Imagine that this is your last moment.  Do you feel right now the way you want to feel at the very end of your life? 


Call it "healthy stress".  It's a fancy term for short-term pressure on a system that makes it stronger.  Cold immersion, saunas, energetic breathwork, high-intensity exercise, intermittent fasting- all of these are hormetic.  Higher doses might cause damage, but the right dose, of the right duration, is a reset signal to your body.  Hormetic activities drive your physiology to an extreme state, and allow it to recover in a controlled fashion.