A sleep expert says parents should start sleep training their babies as early as just THREE MONTHS - rather than "waiting until you're desperate"."

Catherine Hart, 40, specialises in sleep and has helped thousands of exhausted parents get their little one snoozing.

While there are endless suggestions for the best way to do it, she warned there is a common mistake parents often make.

She claims it's often suggested the right age to start sleep training a little one is between four and six months.

But Catherine suggests it's actually better to do much earlier - at just three months old.

She says this is because the older babies get, the more their habits become firm and more difficult to correct.

Catherine - who is mum to Annabelle, six, and Evelyn, four - from Mount Maunganui, New Zealand, said: "A lot of parents don’t realise how much of an impact they can have on their children’s sleep."

"There’s a lot of misconceptions and it's a hugely controversial topic - but parents underestimate what they can do."

"Lots of parents get themselves in a position that is not sustainable at all - and then they can’t get out of it."

"Lots of families these days are already so stretched - raising a child is hard enough then you throw sleep deprivation on top of that."

Catherine said three months is a "great age" to start "getting onto things early" with sleep training."

She claims the older babies are, the more aware they are of their surroundings and can start developing sleep anxiety, compared to at a younger age.

The younger they are, the less likely they are to have hit milestones which add challenges, she says - such as being able to stand in their cot.

Her expert other tips include establishing a consistent nap routine, using a white noise machine, and making sure the room is pitch black.

She said: "People can underestimate the importance of a good sleep environment."

"When they're no longer newborn, they know day versus night, so I'd recommend a pitch-black room - light plays an important role in the sleep and wake cycle."

"A white noise sound machine will also keep a consistent environment and mask any household or external noises."

"You should also pay attention to the room temperature, and ensure the baby is dressed appropriately for it."

"I would say wake them up at a similar time each day, put them down for their naps at the same times each day, then put them to bed in the evening at the same time."

With Catherine and her partner, Conan Dickie, 42, having been through the experience twice with their daughters, she knows firsthand how tough it can be.

She encouraged parents not to be too hard on themselves - and reminds even if they are struggling, it won't last forever.

Catherine said: "With my plans, I think some parents wait till they're desperate - then buy them at 3am when they are wide awake."

"But I promise, even when it feels like they'll never sleep again, eventually they will."

"The short-term phrase going through sleep training is hard, but eventually the family will get to sleep again."

"The days are long, but the years are short - it will get better."

CAT'S TOP FIVE TIPS TO GET BABIES TO SLEEP:

1. Get on a consistent and predictable sleep schedule -babies LOVE routine and thrive on them.

2. Put your baby down for sleep within their age-appropriate awake window.

3. Don't put your baby to bed too late -they get their best sleep in the first 1/2 of the night.

4. Do a bedtime routine -We know from studies children with a consistent bedtime routine from an early age are more likely to go to sleep earlier, take less time falling asleep, sleep longer and wake up less during the night.

5. Teach your baby how to fall asleep on their own. It's that biggest factor that I've faced working with families that will significantly reduce night wakes and ensure longer naps.