New Zealand police are seeking an order to stop a woman from driving, amid concerns that she had driven hundreds of miles while asleep, even sending text messages along the way.
Friends of the woman alerted the police, saying that she has a highly unusual sleep disorder.
She was found slumped at the wheel at a house she once lived in, and told police she had no memory of her trip.
Police said most of the text messages she had sent were incoherent.
A sleep expert told the BBC that although her story stretched credulity to the limits, it was not impossible.
Dr Neil Stanley said that while there had been cases of "sleep driving", "sleep texting" is not so common.
"If she could drive while asleep then it's possible she could also send texts while asleep," he said.
"But if that really happened it would be an extreme case that would truly stretch the limits of what is considered to be possible."
Police said that they received an emergency call just after midnight on Wednesday from a friend of the woman who was worried that she had gone out in her car after taking sleeping medication.
They said that 10 months ago the woman had done the same thing.
Police say that patrol cars were ordered to keep a lookout for her silver hatchback and tracked her via her mobile phone.
They said that data revealed that she was sending texts as she drove from her Hamilton home to the beachside town of Mount Maunganui through Auckland in the North Island, a distance of almost 300km (190 miles).
"We have sought an urgent order forbidding her to drive and to seek medical advice on her suitability to remain holding her driver's licence," Senior Sergeant Dave Litton said.
"While her being found safe and well is a relief for everyone involved, the potential for tragedy was huge."