Thirty students, mainly from the school's Community and Family Studies classes, slept overnight in the multi-purpose centre.

Kotara High school captain Jacqui Willing said her classmates were keen to participate in Vinnies CEO Sleepout for homelessness after learning about the problem in class.

She said they were shocked to learn that 42 per cent of the homeless population fell under the age of 25.

"A lot of people hold on to the perception that homeless people are older men," she said.

"But every homeless person is different and becomes homeless through a different set of circumstances."

The students were inspired to act and decided to organise their own event to raise money and awareness.

They have raised $830 so far, and hope to raise $1500 in total.

During the sleepout the students were visited by a representative from St Vincent De Paul, who spoke about the charity's fund-raising efforts and programs.

This year chief executives from across Australia raised more than $6 million in June's sleepout for homelessness, with contributions from more than 37,000 supporters.

Funds raised in 2014 helped provide more than one million meals, along with 365,164 "bed nights" for the homeless.