(CNN) -- It seems like a cliche -- a powerful politician undone by underpants.
After a weeklong Twitter saga, U.S. Rep. Anthony Weiner, who represents New York's 9th Congressional District, confessed Monday that he sent lewd photos of himself to women, had inappropriate online relationships and had lied about them.
Photos of the married congressman in his underwear surfaced last week, turning Weiner into the center of a possible ethics investigation and an easy target in late-night comedy jokes.
Weiner joins a slew of high-profile men with sex scandals, such as former presidential contender John Edwards, who could face jail time, former California Gov. Arnold Schwarzenegger and former Nevada Sen. John Ensign.
It begs the question: Why does a public figure risk his reputation, marriage and career on a sexual impulse that can become so easily public -- such as sexting?
"Obviously for a politician, these impulses are more risky than for everyone else," said Dr. Marvin Zuckerman, professor emeritus of psychology from the University of Delaware.
Zuckerman describes people who disregard risk and pursue impulses as high-sensation seekers.
They pursue sensations that are novel or intense, such as exchanging flirty banter over social media, sexting or having an extramarital affair.
Jeff Gardere, a clinical psychologist, called it "a sexual Russian roulette" on CNN's "American Morning."
"You are doing something that is so stupid, it is almost crazy, he said. "And so, what's going on with him, quite obviously, he seems to be a man who has some impulse-control issues. He can't just control himself. That's part of it."
In a news conference Monday, Weiner described his actions as "dumb," "destructive" and "deeply, deeply hurtful" -- both for his admitted coverup and for repeatedly engaging in "inappropriate conversations."
"The bottom line here is that he was not thinking," Gardere said. "He was just in a situation where he was just fulfilling his own pleasure principle."
Weiner could have some form of deeper pathology, such as depression, stress or risk-taking, he added.
But high risk taking is not always related to sex. Some risk takers are adventure seekers, mountain climbers or people who seek stimulation, said Zuckerman who wrote a book called "Sensation Seeking and Risk Behavior."
Sensation seekers are bored with the ordinary experience and try to push the boundaries. Every time they get away with an activity, it only emboldens them.
"Every time you experience something risky and nothing bad happens, you extinguish some of the risk," Zuckerman said.
Much like mountain climbers, sensation seekers plan and consider the risks. But they make mistakes or don't anticipate factors. For mountain climbers, this could be a misstep. For Weiner, it's an error in sending a tweet, intended to be private, into the public sphere.
Taking a suggestive photo of one's body parts and sending them to admirers hints at two traits: exhibitionism and narcissism, Zuckerman said.
While it's impossible to know what drove Weiner's conduct, he said most exhibitionists are men.
They display their bodies with no serious intention of following up with sexual acts but want to excite others. And that follows the sensation seeking.
"One feels one's body is so beautiful, it excites people," Zuckerman said. "It excites them to excite or to think it excites other people."
It's impossible to know what exactly sparked the congressman to send private photos of himself.
His behavior indicates a lack of understanding how easily their behavior can be uncovered, said James Cordova, associate professor in psychology at Clark University in Worcester, Massachusetts.
"People are really not understanding how public these forums for communicating with each other are," he said. "This is just another one of those examples, it becomes obvious and inescapably clear that they are public in ways people don't often recognize."
Cordova, who studies couples issues through the Marriage Checkup, said it's complex whether Weiner's cyberactivities qualified as adultery.
Cordova works with couples dealing with the ambiguity of online flirtations from chat rooms, e-mails, Twitter and Facebook exchanges.
"There's something about the computer that enters into a private space," he said. "We think it's more private than it actually is, until it becomes clear that it's not at all private."
What hurts a marriage or a relationship is the "hidden nature" of the person's behavior.
"It's the hiding, it's the lying," Cordova said. "In an intimate relationship, the foundation rests on the freely given trust in each other."
The hiding of an activity or a behavior is what shatters the trust.
"It's about the deceiving the partner," Cordova said. "If this behavior and activity is openly acknowledged in the relationship and the trust isn't violated, then that's different."