Lucy Durack shares the one big mistake parents make when using a baby sleep therapist.

Before she had her daughter Polly, performer Lucy Durack used to think the lack of sleep parents complained about was amusing.

Then she experienced the tired-to-the-point-of-delirium for herself.

“I was at my wits end, absolutely desperate I was so tired and I felt like I was losing my mind so I’ve never felt anything like that. People used to joke about it and I thought it was a funny thing and it’s so not funny,” she told I Don’t Know How She Does It host Alissa Warren.

Listen to Lucy Durack talk about her experience with “sleep angels”. 

“Polly was fine until six months and then she didn’t sleep until 16 months. We had a Sleep Angel for one night but I didn’t really follow through with her techniques so then we got her back.”

The sleep specialist slept in their apartment for three nights.

“It wasn’t so much of, like she was in the room with Polly for the first night and part of the second but then it was, listening to her cries and letting her cry a bit which I found quite traumatic but it ended up giving us our life back because she did then sleep through the night which was amazing,” she said.

Thank you everyone for such kind birthday thoughts and to my next level husband for many birthday surprises including a phone call from Johnny Young fulfilling a life long dream of mine to feel like I was part of the Talent Team. So awesome! Thank you and #goodnightaustralia ????✅????

A post shared by lucydurack (@lucydurack) on Nov 17, 2016 at 3:39am PST

Like most parents, Durack and husband Chris found the experience quite hard.

“I feel sick even talking about it now. In my stomach I felt so, I really didn’t want to, I’d read all this stuff about how if you do leave them to cry for too long then they might have anxiety and depression later on in life and things like that bother me, of course, as they would any mum I’m sure,” she said. (Post continues after audio.)

“It was incredibly stressful but she got there in the end.”

However they didn’t tell anyone straight away that they’d had help for fear it was too good to be true.

“For the first few months Chris and I were like ‘We can’t mention it in case we jinx it’. So Chris was like ‘Let’s not even tell people that we had the sleep angel in case..’ so we didn’t say anything for a few months,” she said.

My little giggling Gladys ???????? #pollygladys

A post shared by lucydurack (@lucydurack) on Nov 22, 2016 at 1:43am PST

“But now that she’s slept for quite a while we’re like telling everyone, ‘oh my gosh get a sleep angel’!