The woman eventually fell asleep on Peterson's couch, fully clothed, the New Plymouth District Court was told on Thursday.
In the early hours of the following morning, she woke to find Peterson trying to remove her pants and bra.
She brushed him away and went back to sleep, only to be awoken a short time later to him having completely removed her pants and underwear.
The woman froze as Peterson began to touch her, a Crown summary of facts detailed.
She pretended to be asleep in the hope he would stop what he was doing and leave her alone.
But he didn't and instead continued to sexually assault her, maneuvering her body in the process to perform different acts.
Realising he was not going to stop, the woman stood up and put her clothes on.
She told him that what he had done was not okay, the summary stated.
In court, Peterson pleaded guilty to two counts of unlawful connection with a female over the age of 16. The charge carries a maximum penalty of 20 years' imprisonment.
Crown prosecutor Jacob Bourke withdrew two charges of rape.
Defence lawyer Julian Hannam asked for the matter to be referred to restorative justice and that the pre-sentence report include electronically-monitored options.
Hannam said he was optimistic the defence would be able to reach the range for an electronically-monitored sentence to be considered.
Bourke said a lot of work would need to be done by defence to keep Peterson out of jail, but didn't rule out the possibility.
Judge Tony Greig read Peterson his first strike warning and released him on bail to return on May 18 for sentencing.
