Police said officers, responding to an unrelated incident, discovered a white Vauxhall Insignia in a ditch on the B2201 Selsey Road at Donnington at about 4.40am.
A spokesman added: "On closer inspection, officers noticed the interior lights were on and a woman was in the driver’s seat. She was identified as Lorraine Smith, an assembler, of Blakemere Crescent, Portsmouth, Hampshire.
"The 49-year-old was helped from her car and was unsteady on her feet. After failing a roadside breath test, she was arrested and charged with driving with 65mcg of alcohol per 100ml of breath in her system. The legal limit is 35mcg."
Police said Smith fully admitted to the offence in a police interview and 'claimed she had swerved to avoid an animal in the road'.
The spokesman said: "At Hastings Magistrates’ Court on January 15, she was disqualified from driving for 18 months. She was also ordered to pay a £120 fine, £85 costs and a £30 victim surcharge."
Smith's arrest came on the last day of Surrey and Sussex Police’s Christmas crackdown on drink and drug-drivers, which ran from December 1, 2018 to January 1, 2019.
Police said a total of 240 arrests were made in Sussex, of which 82 have since been convicted and the remaining have either been charged, released under investigation or released without charge.