The Times ran an article about research that looked at hormone levels and the performance of traders.
University of Cambridge neuroscientists John Coates and Joe Herbert measured the testosterone levels of 17 traders on the London floor twice a day for 8 days. They also measured cortisol levels and looked at how much money the traders made each day.
They found that traders who made more money had higher levels of testosterone than those who made less. Not surprising, when market volatility was greater, levels of cortisol, a hormone associated with stress, were greater.
A particularly interesting finding was that traders who had higher levels of testosterone at the beginning of the day tended to make more money during the day. While this might indicate that higher levels of testosterone could improve performance, the author of the article suggested that very high levels of testosterone could adversely affect performance by leading a trader to make irrational decisions. Not mentioned in the article is the possibility that some other factor(s) might influence both testosterone levels and earnings.
This reminded me of a strange story I posted back in October about a hedge fund trader who was suing his employer claiming that he was forced to take "female hormones" to make him less aggressive.