"The scariest part of it for me was that there were no red flags at all," the 30-year-old Melbourne woman said.

Detective Senior Sergeant Darren Bentley from Melbourne’s Sex Offences and Child Investigation Team (SOCIT) said while the final week of the year was a time of celebration for many, it could also be among the most dangerous.

Sexual assaults can spike in the week leading up to New Year, doubling or even tripling some years, in a surge driven by opportunistic predators.

Alarmingly, these attacks can often occur at end-of-year work functions and Christmas parties at licensed venues.

"It's a time of the year when we’ve got a lot of social functions and parties going on ... there’s alcohol consumption, people are intoxicated and we tend to see a bit of a rise over this period relating back to those type of functions," he said.

“We know that perpetrators are opportunistic and take advantage of vulnerable victims including those who may be heavily intoxicated and incapacitated by their own actions."

Victoria Police are running a week-long social media campaign in a bid to encourage victims to come forward and bystanders to intervene if they see someone being assaulted.

The video campaign aims to bust common myths and misconceptions about sexual offences before end-of-year celebrations.

Each video dispels a common misconception including that "people who are alcohol affected are responsible for their own sexual assault" and "they could have prevented the sexual assault by drinking less".

"When people are heavily intoxicated they can’t ever consent, so the message we want to get out there is that sexual assault is never, ever the victim's fault and that if they report to us, they will be believed and we will take action where we can," Detective Senior Sergeant Bentley said.

"Another major misconception around sexual assault is that it’s this unknown person who comes out of nowhere in a dark alley and while there are those types of offending, a lot of our offences are committed by people the victims know and trust."

He said the process of reporting a sexual assault could also be complicated when the victim knows the perpetrator.

"They are often fearful of how it will further impact them and the people around them," he said.

"It's a breach of their lives and it’s really, really difficult for people to build up the courage to come forward."

But Detective Senior Sergeant Bentley said the key to preventing sexual assaults lay in changing community perceptions.

"We need to generate a culture where it's OK to intervene. When you see vulnerable person at a bar, maybe they’ve had a bit too much to drink, go over and ask them if they’re all right," he said.

"If you see somebody stumbling out to a taxi or being ushered into a taxi by somebody, go and ask them 'do you know where you are going? Do you know this person?' You could prevent a sexual assault and the harm and devastation that comes with it."

Detective Senior Sergeant Bentley said SOCIT had more than 450 dedicated investigators across the state, who were trained to investigate sexual offending and provided support to victims.

Eva now struggles with post traumatic stress disorder and is at times struck down by crippling anxiety attacks.

"It's the hyper awareness I struggle with most," she says. "You become afraid of everything. It’s like when you get into a car and you don’t really think about how dangerous it is ... even though there is always this chance you might have an accident. Your sense of safety is taken from you."

But she said reporting her assault to police also allowed her to regain lost power and control.

"You didn't choose for that person to commit that crime against you- but you can choose to reach out and get the help that you need to get on with your life," she said.

"Getting support, being believed and moving forward actually gave me some of my power back. You didn’t choose to become a victim of sexual assault but you can choose not to be a victim alone."

The Australian Bureau of statistics estimates about 25 percent of women have experienced sexual violence.

Melbourne's South Eastern Centre Against Sexual Assault manager Carolyn Worth said while reporting had increased, it still fell significantly short of the number of victims being sexually assaulted.

"When somebody has been sexually assaulted by somebody in a position of power, particularly at their workplace, it's extremely difficult for them to report," she said. "It's often their livelihood and they may fear the impacts it could have on their career."

But she added sexual assault and trauma services were experiencing a significant increase in demand for assistance as more women speak up in the wake of the #MeToo campaign.

*Name changed to protect identity of victim

Lifeline: 13 11 14; 1800 Respect National Sexual Assault and Family Violence Counselling Service: 1800 737 732