(CNN) Be extra careful of the male lawmakers who sleep in their offices -- they can be trouble. Avoid finding yourself alone with a congressman or senator in elevators, late-night meetings or events where alcohol is flowing. And think twice before speaking out about sexual harassment from a boss -- it could cost you your career.

These are a few of the unwritten rules that some female lawmakers, staff and interns say they follow on Capitol Hill, where they say harassment and coercion is pervasive on both sides of the rotunda.

There is also the "creep list" -- an informal roster passed along by word-of-mouth, consisting of the male members most notorious for inappropriate behavior, ranging from making sexually suggestive comments or gestures to seeking physical relations with younger employees and interns.

CNN spoke with more than 50 lawmakers, current and former Hill aides and political veterans who have worked in Congress, the majority of whom spoke anonymously to be candid and avoid potential repercussions. With few exceptions, every person said they have personally experienced sexual harassment on the Hill or know of others who have.

In an environment with "so many young women," said one ex-House aide, the men "have no self-control." "Amongst ourselves, we know," a former Senate staffer said of the lawmakers with the worst reputations. And sometimes, the sexual advances from members of Congress or senior aides are reciprocated in the hopes of advancing one's career -- what one political veteran bluntly referred to as a "sex trade on Capitol Hill."

These anecdotes portray a workplace where women are subjected to constant harassment -- both subtle and explicit. They also highlight an antiquated reporting system that discourages some victims from speaking out, leaving many professionals on the Hill to rely instead on hushed advice from peers and mentors.

On Tuesday, a House committee held a hearing to examine the chamber's sexual harassment policies , and the Senate last week passed a resolution making sexual harassment training mandatory for senators, staff and interns -- two clear acknowledgments of the need for reform. Both House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell support ramping up sexual harassment training.

One female congresswoman told CNN that she has experienced sexual harassment from her male colleagues on multiple occasions over the years, but she declined to speak on the record or detail those interactions.

"Half are harassers," she said of her male counterparts in Congress, before quickly adding that that was an over-estimate -- only "some are harassers," she said.

Capitol Hill's open secret: 'We know' who they are

What began as a typical workday left one woman feeling "horrified."

A former Senate staffer recalled getting on the "members only" elevator -- designed to let lawmakers easily reach the House and Senate floors -- with her boss a few years ago. Her boss introduced her to another senator in the elevator. Both senators are men and still currently in office.

When she leaned in to shake that senator's hand, he stroked the inside of her palm "in a really gross, suggestive way" -- a gesture that was completely invisible to her boss. The ex-staffer said she was rattled and "felt very yucky." She was also shaken by how brazen the senator was to do this with his colleague standing right next to them.

The woman, who declined to be named or reveal the senator's identity, told CNN that she avoided that lawmaker from that day on. She also never told her then-boss about it -- she was embarrassed and nervous to make it an issue, she said, and simply "took it for the gross moment that it was."

"Nothing about it felt right," she said.

In conversations with CNN, multiple women pointed to the elevators on Capitol Hill as a place where staff and members prey on women and say they have been advised to avoid riding alone with men if possible. One woman said years after leaving her job in Congress, she still feels anxious about being alone in elevators with men.

The inappropriate conduct is hardly limited to the confines of elevators.

The unique lifestyle on the Hill helps fuel a hostile culture. Many male members are far away from their families, including their spouses, during the week, frequently working late nights and attending evening fundraisers and events where alcohol flows freely. Often, they are staffed by younger, female employees. Some members of Congress forgo a Washington-area apartment and sleep in their offices, a practice several sources highlighted as problematic.

One aide who works in the Senate described Capitol Hill as "a sort of old school, Wild West workplace culture that has a lot of 'work hard, play hard' ethos and without the sort of standard professionalism that you find in more traditional workplaces."

The dozens of interviews that CNN conducted with both men and women also revealed that there is an unwritten list of male lawmakers -- made up primarily of House representatives where there are many more members than the Senate -- notorious for inappropriate or predatory behavior. Several people simply referred to that roster as the "creep list."

More than half a dozen interviewees independently named one California congressman for pursuing female staffers; another half dozen pointed to a Texas congressman for engaging in inappropriate behavior. CNN is not naming either of those lawmakers because the stories are unverified.

"Amongst ourselves, we know," a former Senate aide said referring to sexual harassers and their behavior. "There is a certain code amongst us, we acknowledge among each other what occurs."

Some stay silent; others tolerate bad behavior: 'There's a little bit of a sex trade on Capitol Hill'

Even as explosive allegations in Hollywood and media have taken down powerful figures like producer Harvey Weinstein, actor Kevin Spacey, comedian Louis C.K. and political journalist Mark Halperin, on Capitol Hill, it's not clear that a similar a day of reckoning is soon coming to one of the country's most important institutions.

The power dynamics in Washington contribute to this problem. Most offices are staffed by early-career professionals who are trying to make a name for themselves in Washington. They also report directly to members of Congress.

"A lot of it has to do with being in a place where people who have power try to exert it to get what they want," one Senate staffer said, adding that a lot of the most egregious examples happen "on the cocktail circuit" -- where powerful men intermingle with younger staffers outside of the Capitol.

It's "people using their power without any self-control," a former House staffer said. "There are a lot of tales of these guys going out and behaving very badly with younger staffers."

But some women tolerate the advances or even reciprocate them -- everything from flirting to getting physically intimate -- believing that it is one way to climb the ladder.

"There's a little bit of a sex trade on Capitol Hill. If a part of getting ahead on Capitol Hill is playing ball with whatever douchebag -- then whatever," said one female political veteran who worked on Capitol Hill.

Former Rep. Mary Bono said publicly this month that she endured suggestive comments from a fellow lawmaker for years before eventually confronting him. Rep. Linda Sanchez and ex-Rep. Hilda Solis also told the Associated Press stories of repeated inappropriate comments from lawmakers, including some who are still in office.

One woman who began her career in Washington in the 1980s and is now in her 50s, told CNN that she still constantly takes precautions to protect herself from powerful men.

"I think women have to watch where they are and how they are all the time," she said.

Travis Moore, a former aide to ex-Rep. Henry Waxman, started a signature-gathering campaign last week calling on congressional leaders to reform "inadequate" sexual harassment policies in Congress. His letter has gathered over 1,500 signatures.

Moore told CNN that he was deeply affected by a close friend who confided in him that, while she was an aide in the Senate, she received sexual comments from a superior, who was an aide. When she reported the behavior to her chief of staff, she was "questioned harshly about it and her motives were questioned."

The accused aide was not reprimanded and there was no recourse.

'The place where complaints go to die'

Harassment on Capitol Hill isn't always sexual in nature.

Around 2011, Liz was a young and fast-rising aide on the Hill. Her career was thriving and her work was getting noticed. But in the Senate office where Liz worked, her direct boss, a male senior aide, yelled and physically intimidated her.

She eventually sought help from the Office of Compliance, the little-known agency established in part to oversee workplace disputes in Congress. But Liz, whose first name has been changed to conceal her identity, told CNN that this was the implicit but clear message she received from the office: "There's no real case to any of this."

"It is like, the place where complaints go to die," she said. "It was like I was talking to a black hole of people who didn't care."

Years later, Liz, who no longer works on the Hill, said she still wonders whether her decision to report her boss's behavior damaged her career.

When asked to respond to Liz's story, OOC Executive Director Susan Tsui Grundmann said in a statement, "Congress designed us to be a non-partisan, independent process, which means that we are not an advocate for either side."

The OOC, established by the Congressional Accountability Act in the 1990s, has come under fire in recent weeks for what some say are antiquated rules that can intimidate victims into silence.

What's more, the initial proceedings alone can drag out for months.

If a congressional aide wants to file a formal complaint with the OOC, they must first engage in 30 days of counseling. After 30 days, they can choose to go into mediation with a representative of the congressional office that they are lodging a complaint against, which can last at least another 30 days. Then, the accuser must wait an additional 30 days before they can officially file a complaint and pursue a hearing either with the OOC or the Federal District Court.

Multiple lawmakers in both chambers are drafting legislation to change the OOC's protocol for handling workplace complaints.

Sen. Kirsten Gilibrand's forthcoming bill would remove the 30-day waiting period before a victim can initiate the administrative hearing phase of the process. In the House, Rep. Jackie Speier is proposing similar legislation.

There is also growing pressure for more transparency so that the public can see information like the number of sexual harassment complaints filed with the OOC, the number of settlements reached, the dollar figure of those settlements and which offices are receiving complaints. CNN, along with some members of Congress, has requested that information.

Tracy Manzer, a spokeswoman for Speier, said 80% of people who have come to their office with stories of sexual misconduct in the last few weeks have chosen not to report the incidents to the OOC.

And many of those who did said the process was a nightmare, forcing them to stop midway through -- some were told things like, "You can't prove it" and "it'll be a nightmare" to move forward, Manzer said.

The female congresswoman who told CNN that she has been sexually harassed by her male colleagues numerous times said she believed there is little upside to speaking out.

"I need these guys' votes," she said. "In this body, you may be an enemy one day and a close ally the next when accomplishing something. ... So women will be very cautious about saying anything negative about any of their colleagues."

Is that depressing? "I think it's reality," she said.

This story has been updated to reflect that Tuesday's House hearing on sexual harassment has completed.