In the normal course of events steroid hormones spike when we wake in the morning, this steroid surge acting much like a breakfast cup of coffee, and then decline over the course of the day. In this experiment we should have observed traders’ cortisol levels dropping by about 50 percent from morning to afternoon sampling times, but on volatile days they actually increased over the course of the day, some of them by an astonishing 500 percent, levels normally seen only in clinical patients.
