Ninety minutes in, something quietly changes

[Fairman]

Ninety minutes in, something quietly changes

A familiar pattern shows up in trade logs. The first hour is sharp. The second is decent. Somewhere around the ninety minute mark, quality drops, even though nothing about the market has changed.

Entries get slightly earlier or later than the rules say. Stops are moved a bit. A setup that would have been skipped at the start is taken because it looks close enough.

The cause is mental fatigue. Intense attention is expensive, and the ability to hold the rules in mind weakens over time. It does not feel like tiredness. It feels like normal trading, but the numbers show otherwise.

A useful test is splitting the trade log by time since the session began and comparing the results by block. Many traders find a sharp decline after a certain point, and the line is surprisingly consistent from person to person.

The fix is a break, a hard stop to the session, or a rule that trade size or frequency falls after a set time. It costs a few good trades and saves many weaker ones.

Some traders schedule two sessions of seventy-five minutes with a real break in between rather than one long block. The second session often turns out better than the tail of the first would have.

Where does performance start to drop within a trading session?