The actress told The Jonathan Ross Show it's harder than it looks to play an unconscious character as you're so aware of any movement you make.
"You have to be very aware of your eyes, your blinking and other characters coming in and out the room to speak to you so you can't react so that was the hardest thing for me," she said.
"When Barbara Knox [who plays Rita] was doing a scene, she was doing an emotional speech to me and speaking about our memories together and I actually drifted off and I twitched which made her jump so I ruined the whole take for her."
But Michelle laughed: "It was eight hours a day in bed which is my favourite kind of day so I didn't mind that…"
The brunette star left Coronation Street in 2014 after six years of playing Tina McIntrye, who was written out in a dramatic death storyline.
"It was my decision to leave, it took me a long time to make that decision, two years I think it took me to make the final decision, it was a hard decision," said Michelle.
"It was their idea to kill the character. Obviously at first I was a bit shocked because I'd played her for six and a half years but in the long run it helps because it pushes you forward and I went out with a bang so what more can you ask for."
Since then, Michelle's career has been going from strength to strength with acclaimed roles in BBC dramas Ordinary Lies and Our Girl, and an upcoming role in ITV drama Tina and Bobby.
Michelle, 29, added: "I went for a lot of auditions [after Corrie] and got sent a lot of scripts. It is very daunting leaving a soap because you've had the safety net of being in the same character for years and years and it is about making the right decisions and making your own path as well."
THE JONATHAN ROSS SHOW, SATURDAY 5TH NOVEMBER, 9.50PM ON ITV