Sandrine Helene Sellies, 34, who has a fear of flying, had drunk alcohol and taken sleeping tablets ahead of the flight from Hong Kong to Brisbane.
She was seen on the Cathay Pacific plane walking towards a door with an unlit cigarette and a lighter.
She then began tampering with the emergency exit until she was stopped by a flight attendant.
Defence lawyer Helen Shilton said her client had no memory of what had happened on the flight on Saturday, and that she had a history of sleepwalking.
She pleaded guilty to endangering the safety of an aircraft at Brisbane Magistrates Court and was given a 12-month A$1,000 (£429) good behaviour bond - she will forfeit the money if she commits another offence.
