For men, being alone with an attractive woman can be unhealthy. Researchers monitored young male and female subjects tasked with solving a Sudoku puzzle on their own. When men were left alone with attractive women, they experienced elevated levels of cortisol, the body's stress hormone. Consistently elevated levels of cortisol have been linked to heart disease, diabetes, hypertension, and impotency, the Telegraph reports.
"In this study we considered that for most men the presence of an attractive woman may induce the perception that there is an opportunity for courtship," the researchers said. For most men, that opportunity results in "apprehension and a concurrent hormonal response."