The 39-year-old, whose stint on the Breakfast Show lasted from 1998 to 2000, conceded that her social life started to concern show bosses.
Speaking on Chris Moyles Meets The Radio 1 DJs, she said: "I could hardly speak. As the show finished and my high from the night before started to fade, I looked around at the Radio 1 people and thought, 'I might get the sack'."
Ball added: "So something had to give. I know the bosses were a bit concerned about my health - and my mental health.
"I just think it was time to go. Now I look back and think, 'Who walks away from the Radio 1 Breakfast Show?' It was huge. Perhaps I should have sobered up a bit and carried on."