In the study, researchers found that young men who voted for Republican John McCain or Libertarian candidate Robert Barr in the 2008 presidential election suffered an immediate drop in testosterone when the election results were announced.
On the other hand, men who voted for the winner, Democrat Barack Obama, had stable testosterone levels immediately after the outcome.
Female study participants showed no significant change in their testosterone levels before and after the returns came in.
"This is a pretty powerful result. Voters are physiologically affected by having their candidate win or lose an election," said Duke neuroscientist Kevin LaBar.
In a post-election questionnaire, the McCain and Barr backers were feeling significantly more unhappy, submissive, unpleasant and controlled than the Obama voters.
The findings mirror what other studies have found in men who participate directly in an interpersonal contest - the winner gets a boost of testosterone, while the loser's testosterone drops.
Testosterone is a steroid hormone manufactured by the testes that is linked to aggression, risk-taking and responses to threats.
Women have it too but in much lesser amounts and originating from different sources (their ovaries and adrenal glands), which makes them less likely to experience rapid testosterone changes following victory or defeat.
To conduct the study, researchers asked 183 men and women to chew a piece of gum and then spit into a sample tube at 8 p.m. as the polls closed on Nov. 4, 2008.
When the election results were announced at about 11:30 p.m., the subjects provided a second sample, and then two more at 20-minute intervals. Those spit samples were then analyzed for concentrations of testosterone and some related stress hormones.