The trades I regret most did not feel like mistakes while I was making them. They felt like conviction. That is the part nobody warns you about. When your body dumps adrenaline into a fast market, the resulting urge to add size does not arrive with a label saying this is chemistry, not analysis. It arrives feeling like clarity. And when you have been grinding through a long drawdown, the reluctance to take an obvious setup does not feel like fear, it feels like discipline. Same person, same screen, two different bloodstreams, and both times the physiology is doing the talking while you think you are.
Most of what I know here traces back to John Coates, a former derivatives trader who went and did the neuroscience. He measured hormone levels in actual traders on actual desks, not undergraduates in a lab, and the pattern that came out of that work is worth internalizing even if you never look at another endocrinology paper. Two hormones matter for our purposes, they run on different clocks, and they push you in opposite wrong directions.
The two states, and why they feel like judgment
Adrenaline is the fast one. It spikes in seconds when a position rips or a market gaps, and it is the acute response. In the research, rising testosterone and adrenaline during a winning run correlate with traders taking on more risk, and the effect compounds. A win nudges the chemistry, the chemistry nudges risk appetite up, the bigger position wins again, and you get what Coates calls a winner effect. The trader on that curve is not lucky and reckless by coincidence. The winning is producing the recklessness. This is the state where you move your stop to give the trade room, then move it again, and each move feels reasonable in isolation.
Cortisol is the slow one, and it is the more insidious of the two because it does not spike and clear. It accumulates. Sustained uncertainty, a choppy market that keeps stopping you out, a drawdown that will not end, all of that keeps cortisol elevated for hours and days rather than seconds. And chronically elevated cortisol does something specific to how you weigh risk. It makes you irrationally defensive. It amplifies your perception of danger, shrinks your appetite for any risk at all, and makes you see threats in setups that are statistically fine. The cruel timing is that this tends to peak right when volatility is highest, which is exactly when the best asymmetric opportunities show up. So the market hands you the good trades at the precise moment your body has decided everything is a trap.
The reason both of these are dangerous is the same reason they are hard to catch. Neither one presents as an emotion you can argue with. Adrenaline masquerades as sharpness and cortisol masquerades as prudence. You cannot reason your way out of a state you have misidentified as good judgment.
Spotting which one you are in
Since the feelings lie, you have to read the behavior and the body instead. Over time I have gotten decent at catching the adrenaline state from a short list of tells. I am checking the position more often than the thesis requires. I am doing mental math on what the account would be worth if I just sized up here. I feel physically warm, my typing gets faster, and I have an itch to act right now rather than wait for my actual trigger. When two or three of those line up, I am almost never as clear as I feel.
The cortisol state reads differently and takes longer to notice because it creeps. The tells are a background sense of dread that does not attach to any single trade, talking myself out of setups that fit my rules, a shrinking watchlist because everything looks too risky, and a general heaviness where opening the platform feels like a chore. Physically it shows up as tight shoulders and shallow breathing that I only register when someone points it out. If I catch myself using the word careful a lot in my own head, that is usually cortisol wearing a costume.
A rough rule of thumb that has held up for me: if the urge is to do more, suspect adrenaline. If the urge is to do nothing while good trades pass, suspect cortisol. The direction of the distortion tells you which chemical is driving.
Resets that actually move the needle
The useful thing about knowing this is physiological is that the fixes are physiological too. You are not going to think your way flat. You have to change the inputs to the system.
The single highest-leverage tool is your breath, because it is the one autonomic lever you can grab directly. Slow exhales are the key part. When your exhale is longer than your inhale, you are pulling on the parasympathetic brake and heart rate drops within a few breaths. The protocol I use is dead simple and I do it without leaving my chair:
- Inhale through the nose for a slow count of four.
- Exhale through the mouth for a slow count of six to eight, longer than the inhale.
- Run that for about two minutes, which is long enough to actually shift your heart rate rather than just feel like you tried.
- Then, and this is the part people skip, re-read the trade against your written rules before you touch anything. The breathing buys you a clearer window, the rules tell you what to do with it.
The second tool is a mandatory break rule tied to volatility rather than to your mood, because your mood is the thing that is compromised. After any sharp move in your position, up or down, you step away from the desk for a fixed block, ten to twenty minutes, no exceptions and no negotiating with yourself in the moment. The point is to let the acute adrenaline clear before you make the next decision, since adrenaline metabolizes on its own if you just stop feeding it new stimulus. The rule has to be pre-committed and mechanical. If you leave it to judgment you will always find a reason this particular spike is different.
The third tool is exercise, and timing matters more than people assume. Hard training raises cortisol acutely, so smashing yourself in a workout right before you trade can leave you starting the session already elevated. What builds resilience is regular aerobic exercise on a consistent schedule, which over weeks lowers your baseline cortisol and widens the gap between calm and panic. Practically, keep the intense stuff away from your trading window and let the long-term conditioning do the work. A short walk mid-session is different and genuinely helps, that is closer to a reset than a stressor.
Building it into the workflow
None of this survives contact with a live market unless it is external to you. The whole problem is that your in-the-moment judgment is the unreliable part, so any rule that depends on you deciding to follow it in the moment is already broken. Write the break rule down. Put the breathing protocol somewhere you will see it. Keep a one-line note next to your screen that just asks whether the urge right now is to do more or to do nothing, because naming the direction is often enough to break the spell.
The part that has helped me most is separating the decision from the state as much as possible. I set my alerts and my rules when I am calm, ideally the night before, and then in the session my job shrinks to executing what a clearer version of me already decided. Anything that lets me pre-commit while regulated and just follow through while activated is worth building. On Blockcircle I lean on scorecards and alerts for exactly this reason, so the thinking happens on a cool head and the hot-blooded version of me is mostly just pressing the button someone sensible already set up.
You will not eliminate the chemistry. It is older than markets and it is not going anywhere. What you can do is stop trusting the feelings it produces and start reading the state from the outside, then run a reset you decided on in advance. Most of the edge is just not making the worst decision at the worst possible moment, and that decision almost always has a hormone behind it.