PLAYERS who are knocked unconscious or have to be carried from the field because of a head injury should face a mandatory week on the sidelines, according to an Australian-first study on football concussions.

In research that reflects the direction the AFL has taken in recent years, the Deakin University study found that sports concussions have a long-term, negative, impact on the brain.

The brain function of 20 retired AFL and state league players and 20 amateur footballers were investigated and compared with healthy people of the same age who have never played contact sport.

Neuroscientist Dr Alan Pearce said the study had shown memory, reflexes and muscle coordination could all be impaired by sports concussions.

He said a mandatory rest should follow a serious concussion at all levels of the game.   

"With the results of this study now in, it is time that football clubs at the elite and amateur level put in place more robust policies to care for concussed players that include mandatory periods of rest following a concussion," Pearce said.

"While incidents seem to be on the rise, with an estimated six to seven injuries per team, per season, at all levels of Australian football each year, we have previously been unaware of the long-term effects of repeated sports concussion."

The AFL has no set time for players to sit out after a concussion, but clubs are expected to follow a protocol that ensures they pass a series of tests before returning to play.

A League spokesman told the issue had been at the forefront of player welfare matters in recent years and will continue to be a matter of key importance.

Recent AFL initiatives have included Tribunal and Match Review Panel changes around head contact, stricter guidelines for monitoring head concussion on match day and the use of the substitute while players are being assessed for concussion symptoms.

Last month the AFL and the Florey Institute of Neuroscience and Mental Health announced a research initiative targeting former AFL players as part of the ongoing research into concussion and mild traumatic brain injury.

Pearce told his major concern was in amateur sport where players didn't have the same support as elite athletes.

"I think if AFL players can engage with the whole concussion issue then it will filter through," he said.

"But if professional players are still doing the mateship and commitment thing (and trying to play the following week) then it's not going to get through.

"I think we almost need a cultural change from the top that's driven by the players themselves, rather than being told by the doctor they can't play."

The AFL hosted a national concussion conference at Etihad Stadium on the eve of the 2013 season and works to educate community clubs.