Key takeaway 1 : Stress is a mismatch between our internal and external experience

Stress is a generic response. It was not designed for a particulr thing. So the "typical" explanation that is given that stress is a relic from human's past when we were chased by animals and enemies and that we are stuck with today because it's confused with something else by the brain and body (e.g. pressure at work, …) is false.

Stress as it exists today always existed. In ancient times, people already stressed about their relatives, how they were doing, … So it already wasn't just related to animal attakcs.

Key takeaway 2 : Since stress is a generalized respose, it offers advantages and disadvantages

Since stress is a generalized response, it has the "disadvantage" that it can easily take over and mobilize a lot of systems. The corollary is that there exists, within ourselves, a lot of pathways to put a brake on stress. And therefore practical tools to mobilize these pathways.

Everybody is born with tools to control stress. Either to amp it up or cool it down.

Key takeway 3 : Since stress is generic … stressors can be physical or psychological

Given that the stress response is generic, stressors can take many forms. Being outside without appropriate clothes on a cold day is stressful. Taking many exams at once is stressful. Two very different stressors, one stress response.

Key takeaway 4 : The acute stress response

A chain of neurons, called the sympathetic chain ganglia and located in the middle of the body and going from the neck down to the navel (a little bit lower), releases acetylcholine when the acute stress response hits.

This acetylcholine will trigger epinephrine release at several sites in the body. And then this adrenaline will trigger several things. Either blood rushes towards required parts of the bodies (legs, heart, …) or to inibite unnecessary parts (digestion, reproduction tissues).

So the acute stress response will want to make you move. And therefore, dealing with stress requires the capacity to deal with agitation.

Key takeaway 5 : Impacting the stress response

The opposite of the sympathetic nervous system is the parasympathetic nervous system. This part of the nervous system controls thing like pupil dilation, face expressions, air channels, … and it is associated with calmness.

And it has entry points. Meaning, one can influence the parasympathetic nervous system through certain practices. And the most potent practice to activate this system and therefore diminish the stress response is breathing practice

Key takeaway 6 : Direct grasp on your stress ? Play with your inhale and exhale!

When inhaling, lungs take more space, diaphragm moves down and this causes the heart to have more space for itself. The heart being bigger, the blood is at a lower pressure and therefore moves slower and a group of neurons signal that to the brain which in turns speeds up the heart to counterbalance. The contrary is true when you exhale.

So … To calm down and slow down the heart, make your exhale longer or more vigorous. To become more alert, make your inhale longer or more vigorous.

The strength of this breathing is that it does not require practice. It's just a true physical and mechanical grasp on the stress response.

Now, to increase its effect, one can top that up with the physiological side of things instead of just the mechanical side. And to do that, one just need to do a double inhale exhale. Doing this, will inflate the sacks that cover the lungs and will make the exhale more efficient at blowing out the CO2.

To Huberman's knowledge, the double inhale exhale technique is the fastest way to calm someone down. And it's in fact a reflex that people do for example when they are trying to recover from crying.

Key takeaway 8 : Wim Hof breathing to combat infection

Wim Hof breathing (Or Tummo or super oxygenation) allows one to mimic a stress response and release epinephrine. Taking a cold shower or an ice bath does the same thing.

And a study showed that performing such breathing allowed to combat infection very efficiently. And this makes sense given that epinephrine increases our immunity.

Key takeaway 9 : If short-term stress is good … What is too much stress ?

Too much stress is when it comes complicated to get a good night sleep.

Key takeaway 10 : Midterm stress, a definition

Midterm stress is when one feels that any additional stress would tip him over the edge or when he realizes that some little things make him react way more than usually (small frustrations turn into big events, …)

Key takeaway 11 : How to handle midterm stress : stress inoculation

Better handling midterm stress requires one to perform something similar to exposure therapy. One needs to expose himself to stress and to learn to handle that stress in a kind of peaceful way mentally.

So, in some way, it's contrary to the popular saying that body and mind must be one. In fact here, according to Andrew, it's all about dissociating the body and the mind. You body is exposed to stress but the mind msut learn to remain calm when faced with the stress response.

One practical tool to perform this dissociation is through the vision. One when stresses out, the pupils dilate and create tunnel vision. Therefore, by doing the contrary of tunnel vision, which is enlarging our vision, having a sort of panoramic view (this does not mean turning your head left and right it means enlarging your field of vision, not focussing on one specific point in your vision), this will calm the system down by playing with the autonomic nervous system.

Key takeaway 12 : Long-term stress

Long-term stress issues are linked to the Serotonin system. And to increase serotonin, people need to do things they love or to connect to things they love (things, pets, people). It's why some antidepressants drugs use the serotonin pathway. The issue with that is that serotonin blunts some aspects of our life because it's a "I have enough" neuromodulator and therefore people may suffer from a lack of libido and things like that.

Key takeaway 13 : Tackykinin

If someone does not have enough social interactions, Tackykinin which is a sinister molecule will start building-up signaling one that he does not spend enough time with people he trusts.

Tackykinin is like an irritant to our system. It depletes good functions (immunity, …) and increases bad ones (fear, irritability, paranoia, …)

Key takeaway 13 : Gratitude

Taking sometime to recognize your moments of bliss, delight, joy, … can positively impact long-term stress. That's why personal journaling helps some people. Because they realize they have those moments in their life and this is enough to trigger the serotonin pathway.

Key takeaway 14 : There is no such thing as adrenal burnout

Adrenals have enough to support 200 years of stress. However, there is something called adrenal insufficiency with impaired adrenals that can make it seem like adrenal burnout.

Key takeaway 15 : Matching internal state with external state is key

When our internal state (stress or calmness) matches the demand imposed on us (external state), then that's good. The opposite is true. And it works both ways. So feeling (internal model) stressed about something that actually turns out to be easy isn't good as well as feeling calm about something that actually turns out to be though isn't good either.

And this mismatch, in the emotional context, is called valence.