The $8 Kmart hack mums swear by if your kids are scared of going to the bathroom at night.

It was seemingly designed as a joke Kris Kringle gift – but mums have found a genius Kmart product is actually perfect for helping with one of kids’ biggest fears.

Mel Thitchener‎ was shopping in the Christmas section of her local Kmart in the Central Coast this week when she came across an $8 Toilet Seat Night Light.

“It is just a jokey gift from the Kmart Kris Kringle section but I thought it could be used in a more practical fashion all year round,” she told Mamamia.

Mel took the light – which is motion activated to only turn on when it’s needed and turn off when it’s not – home and installed it on her loo as a way to help her kids during any midnight toilet trips.

The product in its packaging. Image: Mel Thitchener.

"We’ve had the light for the last two nights and my kids  - five years old and nine years old - are really happy with it.

"It saves blinding yourself by turning on the full light and the motion sensor and automatic turn off means you aren’t wasting batteries all night."

Mel was so happy with her night light hack, she shared it on the Kmart Mums Australia Facebook group. And it turns out, the product is a favourite among mums, especially for toilet training.

"We have one and it’s great. No more sitting on pee on the seat or stepping in pee after my little man goes to the loo in the middle of the night," one mum said.

"Perfect for little ones going to the toilet at night!!!" wrote another mum.

"This would be great for toilet training!" commented another.

Dozens more mums were so impressed they said they were going out to by one as soon as possible. Since the time of Mel's posting, it has also been liked 1700 times and has almost 350 comments.

Mel says the toilet light, which simply hooks onto the bowl under the seat, can be set to blue, change colours and circulate through the rainbow.

While the product doesn't appear to be available online or at every single Kmart store, customers can call ahead to see if their local store has it.

What are your toilet training tricks? Tell us in the comments section below.