"It was cruel and unusual." After years of insomnia, Anna signed up for 'sleep torture'.

Anna Guthleben has always been a night owl.

She tends to have a bit of a slump during the day, but perks right up at about 10:30pm.

This was fine in her 30s, when she was still studying as a mature-aged student, but when she entered her 40s and started working in “real jobs” that required a bit more routine, she realised her sleep patterns were a problem.

“It really came into my consciousness then that I couldn’t cope,” the now 57-year-old told Mamamia. “I don’t get to sleep easily. I never go upstairs to go to bed and think I am going to sleep. That’s not what happens for me.”

In 2017, Anna stumbled on an advertisement on Facebook for a sleep experiment at Flinders University.

WATCH: The professor in charge of the sleep trial on SBS. Post continues after video.

They were looking for participants with chronic insomnia, particularly those who have trouble falling asleep. She thought she would be the perfect candidate.

Little did Anna know that by agreeing to the Intensive Sleep Retraining (ISR) treatment, she was essentially signing up for sleep torture.

With an iPhone strapped to her arm and an earpiece in place, Anna settled in for the ‘experimental’ night sleep.

Every few minutes, the phone made a very gentle ‘ping’ noise at a particular note, and she’d wiggle her arm to let the phone know she was awake.

If she slept through it, it would vibrate to wake her up and she’d have to get out of bed for three minutes before being allowed back in.

“The third time that happened I was like ‘oh shit, what have I done,'” Anna told Mamamia. “It was cruel and unusual punishment, but it was only one night…. So for someone like me who has spent years sleep deprived, one night is fine.”

After that one night, everything changed.

Anna describes it as “black and white” or “night and day”. The results were instantaneous.

“It was amazing. Thinking back on it now, it makes me quite emotional,” she told Mamamia.

After being required to stay awake the next day, by the following night, Anna's head hit the pillow and she instantly fell asleep. It wasn't just that first night either, it continued for months and months.

She'd walk upstairs confident that she was about to go to sleep every night. For someone with insomnia, this is life changing.

ISR is based on the idea that prolonged sleep deprivation leads to the accumulation of sleep pressure, which inevitably leads to sleep. In a single night a participant could 'fall asleep' up to 48 times, which allows them to feel what it's like to fall asleep and recognise that they are capable of that. It also allows insomnia sufferers to separate the feeling of sleepiness and fatigue.

It's a technique that's been around since the 1980s, but as Dr Michael Mosley will tell SBS Insight on Tuesday night, it hasn't yet "got out there" into the mainstream. Mosley does say the treatment can take 6-8 weeks to really kick in.

But as the professor in charge of Anna's treatment program, Professor Leon Lack, explained to SBS,  they've managed to condense the whole process into 24 hours, and Anna is testament to the fact it works.

After three months of incredible sleep, a number of factors in the form of job loss, house loss and breast cancer put Anna under incredible stress, and it undid the behavioural psychology of ISR.

As she told Mamamia, she's through the other side of all of that now, and is keen to go back to Professor Lack for another round of torture.

Feature image: SBS. 

You can hear more about Anna’s story and other sleep hacks tonight on Insight at 8.30pm on SBS.