Naomi Jacobs, who lives in Manchester, could not remember anything past 1992 and thought she was about to sit her GCSE exams at school.
Medics said she was suffering from transient global amnesia - a form of acute memory loss brought on by stress.
At the time, the single-mum was studying for a psychology degree as well as running a homeopathy business.
As the 'episodic' part of her memory shut down, she lost all her emotional recollections.
Naomi told the paper how she burst in tears when a strange little boy appeared and called her 'mum - it was actually her son Leo, but she had no recollection of him at all.
She was also in for a shock when she looked in the mirror and saw an older woman staring back at her.
'I fell asleep as a bold, brassy, know-it-all 15-year-old - and woke up a 32-year-old single mum living in a council house. The last thing I remember was falling asleep in my lower bunk bed, dreaming about a boy in my class.
'When I woke up, this little boy appeared and started calling me 'mum'. That's when I started to scream. I didn't know who he was. I didn't think he was much younger than me. And I certainly didn't remember giving birth to him. I began sobbing uncontrollably. To say I was petrified was an understatement. I just wanted my mum. I couldn't get my head around going to bed one night and waking up in a different century.'
Naomi, who is now 35, went on to make a full recovery. She says the episode was 'not fun' and instead of being like Michael J Fox in Back To The Future, she had 'fallen asleep in a world of endless possibilities and woken up in a nightmare.'
How would YOU feel if you woke up thinking you were 15? Recon it would be fun or scary?