Tilt is a term borrowed from poker, where players make uncharacteristically bad decisions after a bad beat. In trading it manifests as oversizing, revenge trades, abandoning a plan, or grinding through fatigue.
The biology is real: stress raises cortisol, narrows attention, and biases risk-tolerance toward 'get it back.' Researchers at Cambridge measured cortisol levels in London traders during the 2007–2008 crash and found markedly impaired risk assessment correlating with elevated stress hormones.
Common operational signs: position size jumps mid-session; you take trades you didn't plan; you stop journaling; you double-down after a loss to 'catch up.' Your own journal often shows the pattern before you feel it.
Generally accepted countermeasures (descriptive — your mileage will vary): a daily loss limit, a forced break after N consecutive losses, written rules that pre-commit to position sizes, and a journal review of past tilt episodes so you recognize the early warning signs in yourself.