BOULDER, Colo. -- Boulder Valley school officials are worried about a new game sweeping the nation's middle schools.

It is called the "choking game" or "pass-out game" and it has resulted in at least eight deaths nationally.

The game is played by squeezing or putting pressure on another student's neck or chest to cut the flow of oxygen. It results in a feeling of lightheadedness. Once the pressure is released the player gets a brief rush after the blood flows back to the brain.

Boulder parents are being told to look for signs their kids are playing the game, including bruises around the neck or bloodshot eyes.

Angevine's Principal Isolbel Stevensen learned some middle school students were playing the game after one student fainted, the Boulder Daily Camera reported. She called an assembly when the the practice didn't stop and also sent a letter home to parents last week.

Katy Fleming, the Boulder Valley school district's health education coordinator, said she first heard about Boulder kids playing the game a couple months ago.

Jan Hittleman, a psychologist with Boulder's Compass House said its "the newest strangest thing." The game is also called "the funky chicken" and "flatliner."