http://www4.gsb.columbia.edu/ideasatwork/feature/735403/Powerful+Lies

The researchers found that subjects assigned leadership roles were buffered from the negative effects of lying. Across all measures, the high-power liars — the leaders —resembled truthtellers, showing no evidence of cortisol reactivity (which signals stress), cognitive impairment or feeling bad. In contrast, low-power liars — the subordinates — showed the usual signs of stress and slower reaction times. “Having power essentially buffered the powerful liars from feeling the bad effects of lying, from responding in any negative way or giving nonverbal cues that low-power liars tended to reveal,” Carney explains.