Police discovered a list of 89 names in a note on his phone under headings of "sex" and "relationships" after one of the 11 women reported the 25-year-old for rape.

Officers have been able to contact 80 of the women - 19 disclosed sexual offending against them by the man.

Six decided not to pursue police action, two are considering their options and 11 made statements against him, police have revealed.

The man cannot be identified because some of the offending dates back to 2011, when he was aged 15.

The South Gippsland man was granted bail by a Victorian magistrate on Thursday afternoon, despite opposition from police and prosecutors.

The prosecutor described the 21 charges of rape, sexual and indecent assault and reckless conduct endangering serious injury as some of the most serious he has seen in his career.

He described it as predatory and grooming behaviour that dated back at least 10 years.

The allegations came to light after a 29-year-old woman reported she had been raped by the man in 2019.

He was arrested and told officers he suffered from a condition called sexsomnia.

Sexsomnia is a disorder that leads a person to engage in sexual acts while they're sleeping. It has appeared in the Diagnostic and Statistic Manual of Mental Disorders since 2013.

The man said he had not been formally diagnosed but had "formed his opinion based on advice from previous partners".

The man gave officers the names of former partners who he said could verify his claim, prompting officers to contact all the women on his sex/relationship list.

The incidents date back to 2011 and involve women who were aged between 14 and 29 at the time of the alleged incidents.

He's accused of raping and sexually assaulting them while they were in bed or as they slept.

One woman confronted the man the following morning and he allegedly told her he had no memory but was aware from previous relationships he had "done similar things" in his sleep.

He smirked at another woman when she asked him about an incident the previous night, telling her later he suffered sexsomnia and had no control or recollection.

Detective Leading Senior Constable Shane Kew said the man apologised in advance to one woman, who was staying with the man during a COVID-19 lockdown, warning her not to wake him if something happened.

After he allegedly sexually assaulted her, he told her it was not his fault and she should wear more clothes to bed to stop him, Det Kew said.

The man is also accused of grabbing another woman by the throat, choking her to stifle her complaints and prevent her from resisting during an alleged rape.

The man's parents offered an up to $20,000 surety to secure his bail and said he could live with them.

Det Kew raised concerns with that, given some of the alleged offending occurred in his family home.

"There was concerning behaviour he was allowed to get away with as a child. I can only imagine as an adult there's even less level of control," he said.

But the magistrate highlighted delays in the case and said the risk he posed could be mitigated to an acceptable level.

He's banned from using dating apps and social media, must live with his parents and abide by a curfew.

Australian Associated Press