Most of us are familiar with the name Sudden Infant Death Syndrome or SIDS, a heartbreaking condition where sleeping babies for some reason, don't wake up.

To just be told that there's absolutely no explanation as to why your healthy child goes to bed and doesn't wake up the next morning is....unbearable.

But neuropathologists at Harvard's Medical School in Boston have made groundbreaking discoveries - they now know children have been dying of the same SIDS disease up to six years old.....but for so many years, it didn't have a name.

Infants then went on and died in the second or third year who had the same underlying problem.

It's called SUDC - Sudden Unexplained Death in Childhood - when a child is older than 12 months, but has the same lack of symptoms as SIDS - when an infant dies of unexplained causes under 12 months old. The difference is just the child's age.

Sudden Unexplained Death in Childhood - over 12 months old

Sudden Infant Death Syndrome - under 12 months old

Historically we have thought of as the age of 12 months as a complete break.

But through our work and the work of others we're beginning to realise there may be a continuam.

Valen was a beautiful little boy, he was the kind of kid that would go into daycare and help another child, he was the kind of kid that would want to kiss someone if they fell over.

Last year little Vaelen Hewitt spent the morning at the beach. He came home and his mum Britt put him to bed for an afternoon nap, he was two and a half years old.

When I put my son to bed he was a healthy little boy I don't think anyone could've been as shocked as I would was, to go in and wake him up and he didn't wake up.

Britt says she knew all about SIDS and did everything by the book to keep her little man safe during that first year high risk period.

I remember thinking when he got to about one year old, oh, I did all the right things, I put him on his back, I kep the room ventilated I kep him cool, I kep him warm enough and for that to happen on the 13th April at 2 years 8 months was a total shock.

But little did Britt and Glen know, their little boy wasn't out of danger.

To not get any answers to your questions you can't reflect and think you know if just done that one thing differently I have a thousand things I could've done differently I have no idea if they would've made a difference.

We didn't get a chance to really find out what his passions were you know he showed some signs of some things you know he loved cars he loved animals, he loved the beach 38.12 I would've done my best to make sure he loved cricket.

By not having an answer we don't know are there things we're doing that could put Palace at the same risk.

The problem is the number of SUDC cases in Australia is unknown because there's been no official recording system for the disease. But in America where they've been collecting data,

SUDC kills one in every one hundred thousand children. Compared to one in every five thousand babies who die of SIDS here in Australia.

Although it's rare it has happened to them and it does happen to people

Doctor Hannah Kinney is one of only a handful of SUDC researchers in the world. In the past ten years she's studied more than 200 cases of unexplained deaths in children from one to five years old.

It's like a pie and you can cut the pieces of the pie and you'll have different diseases that result in the sudden death of children

But the largest category is unexplained.

Incredibly, Doctor Kinney has found the majority of SUDC toddlers have the same brain abnormality in an area called the Hippocampus....crucial for controlling the child's heart beat and breathing.

It prevents the hipcoampus from functioning normally particuarly during the sleep and it can result in abnormal wiring and sudden discharge and affect the brain stem and result in sudden death.

In many of these cases, Dr Kinney has also found a history of Febrile seizures in these unexplained child deaths....little Vaelen had a Febrile Seizure just a year before he passed away.

In the story with the Hippocampus, we found that 60% of those children had a history of a febrile seizure - a seizure with a fever or family history of febrile seizures.

Febrile Seizures are fairly common in toddlers, it's when their heart suddenly beats a little slower or their breathing stops briefly ....and now this information could give parents a warning to take extra precaution.

We give this information to the clinicans and they are in the process of devising new guidelines around the treatment of children with febrile seizures.

You just think they're in the clear after 12 months.

Like the Hewitt's Robert and Kylie Trewin say they too had never heard of SUDC.

I remember that morning him just apologising to me and just repeatedly saying I'm so sorry, I never had a second where I doubted that wheat he'd done or how he'd look after Coops.

Little Cooper was sixteen months old, he'd learnt how to stand ....

Oh good boy, good boy

and walk....

But when his dad put him to sleep one night five years ago, little Cooper never woke up in the morning.

When I walked into the room, the room was cold, I just had a feeling and I could see he wasn't natural in the cot and as soon as I touched him he was cold.

If we had've had a monitor on his cot, chances are we could've taken it off after he turned 1, because we had no idea that this could happen at this age.

Determined to find answers, Rob and Kylie found there was no research into SUDC in Australia. So they started the Cooper Trewin SUDC research fund, raising more than $360,000 for Dr Kinney and her research team, who have now set up a base in Melbourne.

We need to get that awareness out there if we can just save one child, then it's all been worth it but we need to tell as many people as we can about SUDC and how you can monitor your children.

Once you reduce your SIDS deaths then you'll look for the other causes and you're going to find realise that you know once that's down then the SUC really are more of a problem.

Perth Paediatrician Dr Jacky Scurlock has worked in sudden infant death for more than twenty years and says more money needs to go toward this research.

The more we learn about all mechanisms of disease um death the better we're able to cope and understand perhaps able to prevent.

Until then, Dr Kinney says parents can only do their best, but should remember the basics,

when your baby is under a year old don't sleep in the same bed and make sure they're put to sleep on a firm mattress on their back. Keep the room ventilated and don't let them overheat.

And after that vulnerable 12 months;

As we get into toddlers um and particularly toddlers with history of febrile seizures to control the fever quickly when they arise and also just good general paediatric care and constant vig vigilance.

As for little Vaelen's family, well his Aunty Lynette Hewitt's doing her best to make a splash.

I just felt like I had to do something and I said I'm thinking I've got to do something tough so what about I swim to Rottnest and back.

That's right, Lynette's swimming from Cottesloe to Rottnest AND BACK to raise money and awareness for Kids and Sids, that's a forty kilometre swim - a feat few have ever achieved.

Anything's possible when you've got a little angel there with you.

On a mission hoping that one day, both of these families might have answers to why their little men aren't here today.

We're asking anyone that has kids, that loves a kid, that knows a kid, to please donate so we can solve this mystery, so we can get answers so we can buy that piece of the puzzle.

Donate here:

Vaelen Hewitt

Cooper Trewin