A 16-year-old QLD schoolgirl has died at a friend's sleepover.

A Toowoomba family has been devastated by the death of their bubbly 16-year-old daughter who died in mysterious circumstances during a sleepover on the weekend.

Kaitlin Barton collapsed and died suddenly while camping in the backyard of a friend’s house in the early hours of Sunday.

She was remembered as a “cheeky, bright, bubbly person” and a “friend to all” by her older brother Nathan, who has set up a GoFundMe page to help with funeral costs.

“No one plans to bury their child and my Mum & Dad are now struggling to find funds to bury their only daughter and give her the send off that she deserves,” wrote Nathan, 19.

The Harristown State High School student was an army cadet who aspired to join the defence force when she finished school, Nathan said.

“Our world is a little darker without the light that is Kaitlin. I feel sorry for all those people that never got to know my sister because they missed out on someone special,” he wrote.

Kaitlin’s aunt, Emma Sutton, told the Toowoomba Chronicle her death may have been caused by energy drinks, saying her niece taken a six-pack to the sleepover.

“She collapsed outside of her tent; we aren’t sure why she had gone outside but she never made it back in,” Ms Sutton said.

Police say it’s not yet known what killed the teenager.