But Edward Press, 58, who has been handed a nine-month jail term, is likely to walk free in the new year after serving most of his sentence on remand.
After groping his victim, the pervert then battered another woman who confronted him, repeatedly punching her in the head in Grimsby, Lincolnshire, on July 6.
He admitted the sexual assault and assaulting the second woman at the town's crown court but after being held on remand since July 14, he is expected to be released shortly.
The court heard Press "took leave of his senses" and let his "wholly disagreeable passions" get the better of him.
Craig Lowe, prosecuting, said Press had been drinking heavily when he sexually touched his victim in the summer.
She was face down in bed but awoke to find him on top of her, the court heard.
Mr Lowe said: "She reacted, threw him off and said: 'What are you doing?'
"He sat there quietly and said he was sorry."
The second woman was told about the sickening attack and confronted Press.
There was an argument and he punched her with some force.
The assault continued and there were two further blows to her head, the court heard.
She may have been knocked out for about 10 seconds but recovered and pushed and slapped Press.
The court heard Press had admitted breaching sex register notification details imposed at Basildon Crown Court in 2004 for a sexual assault.
He was banned from being with children in an address for certain periods of time but breached this by having children and a woman stay over.
Andrew Bailey, mitigating, said it was an unpleasant series of offences.
Judge Jeremy Richardson, QC said Press drank "vast amounts of alcohol " and, as a result "you took leave of your senses".
"It was a nasty episode," said Judge Richardson.
Press admitted his "wholly disagreeable passions" and the incident was "deeply unpleasant" for the woman in bed.