The woman was in the downstairs sitting room of her home in Ballinacurra Weston when a man broke in and grabbed her.
The intruder was wearing a balaclava when he entered the house at around 1am.
When the woman put up a struggle and screamed for help, her attacker ran from the house.
A garda spokesman said: “She was extremely lucky as this could have been far worse but for her screams, which were heard by members of her family who were upstairs.”
Gardaí yesterday arrested a man and questioned him in connection with the attack.
Roxboro gardaí are also investigating an attack at an apartment at Mulgrave Street in which three men smashed down a door and assaulted two residents.
During the attack the intruders produced a knife and threatened the residents. More than €600 and several items were taken.
Meanwhile, a prisoner who escaped from the custody of prisoner officers while attending the Mid- Western Regional Hospital on August 28 was yesterday re-arrested and returned to Limerick prison.
Roxboro Road gardaí spotted the runaway prisoner at a shopping centre near the Childers Road.