An Auckland principal says there's only so much schools can do to police an online game that's taking a toll on students.

Papatoetoe High principal Vaughan Couillault says the game, called Fortnite, is designed to be addictive.

He says some of his students arrive late because they've been playing the game until 2 or 3am.

Couillault told Mike Hosking of one primary school that has sent a note home to parents - asking that the game not be brought to school.

"We can help to educate and sort of get the message out there. Most principals really just want to get on with the business of what happens in the classrooms and on the campus."

LISTEN ABOVE AS VAUGHAN COUILLAULT SPEAKS WITH MIKE HOSKING