The Science Behind Adrenaline

January 16, 2016

It’s an experience no doubt familiar to everyone who has experienced a moment of fear, stress, or excitement: a rapidly beating heart, keener senses, and an almost limitless supply of energy. For a few minutes at least.

That momentary burst of oomph is largely started by our body’s ramped up production of the hormone adrenaline (and its accompanying partner chemical, noradrenaline).

Since its discovery at the turn of the 20th century, adrenaline has come to be associated with all sorts of phenomenal feats and attributes: from resurrecting the dead to either turning people into temporary superheroes or reckless addicts enticed by the very prospect of danger (adrenaline junkies). As with most things, though, the real truth lies somewhere in the still very cool middle. So let’s go ahead and take a honest look at the little hormone with a big impact.


Adrenaline, at its simplest, is part of our innate response mechanism to perceived external stress. When something threatening or exciting comes into our rear view mirror, the body undergoes a series of subtle internal changes to better prepare for and/or avoid whatever’s headed our way. These adjustments are collectively called our “flight-or-fight” response.

For those particularly inclined to step in front of danger, though, such as skydivers, there’s probably room to include a third “F” — Fling.

When flight-or-fight kicks in, adrenaline is primarily released from its namesake organ smushed on top of our kidneys, the adrenal gland. Working in synergy with noradrenaline (mostly released from our central nervous system), adrenaline is pumped throughout the body via the bloodstream and, depending on which cells it comes into contact with, prompts a multitude of effects.

A short, though not exhaustive, tally of adrenaline’s influence includes increased heart rate and glucose production, better respiration, and more efficient oxygen use by our muscles, which in turn boosts our strength, speed and endurance. Because it temporarily helps shut down our immune response and other non-essential bodily functions, adrenaline is even used to treat severe allergic attacks, or anaphylaxis.

If our body was a tricked out, fleshy street racer, adrenaline could best be thought of as our nitro fuel, ready to jump in at a moment’s notice and push us over the finish line.

Cart Before The Horse

Crucial as adrenaline is to our survival, its close relationship to how we experience excitement and fear has led early scientists and the public alike to overstate its powers, according to Dr. Brian Hoffman, professor of medicine at Harvard Medical School. Hoffman would know better than most, being the author of the 2013 book Adrenaline, a self-styled biography of the hormone.

For instance, when we talk about seeking an “adrenaline rush,” we’re likely thinking about it in terms of a recreational drug — as if the very release of adrenaline will turn us into insta-daredevils, similarly to something like cocaine. But that’s mostly wrong.

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