O'Shea's admission comes as Peter Robinson yesterday warned that "concussion can be fatal" after his teenage son Ben died during a schools rugby match this month four years ago.
The 2013 All Star clashed heads with Cillian O'Connor during last August's defeat to Kerry in Limerick, a collision which he felt had a "fairly significant" influence on the outcome of the game.
The incident occurred in first half injury-time with both players being replaced by at half-time before O'Connor returned in the 42nd minute and O'Shea seven minutes later. It came just seven weeks after he was knocked out in the provincial final victory over Galway.
O'Shea admits to being concussed in the Gaelic Grounds having first suffered the condition as a 16-year-old. "It happens quite easily to me," he said.
He acknowledged he wasn't the best judge of his situation at the time. “It’s very difficult when you’re in the heat of a game like that and you think you can make a difference, regardless of what state you’re in, to be objective and make a call like that. I wanted to get back on the pitch. I came back on the pitch when they just scored a penalty, I think, and I suppose you’re thinking you can make a difference.
“It’s a difficult one to call. I know James (Horan) and myself had a long discussion on the sideline about it at the time, but it’s always very difficult from a player’s point of view."
O'Shea added: "I think maybe from my own point of view, that it's happened so much, when it does happen, if it does happen, I need to be more team-focused about it, not thinking about myself, and thinking more that someone who comes off the bench would be more ready to give it 100%."
The 24-year-old suggests a centrally-appointed doctor may be a solution to a growing issue in Gaelic football. "Well, there probably should be an independent doctor maybe on the sideline to kind of dictate what happens. Maybe a GAA doctor who’s independent of both teams.”
Acquired Brain Injury Ireland spokesperson Karen O'Boyle said the idea is good but stated either the team doctor possibly in conjunction with the referee should be able to make a call on the well-being of the player.
Looking ahead to the 2015 season, O'Shea concedes Mayo have to improve their game management. "At the moment when we put ourselves six or seven points up, which we have done, it's still not seen as a dead game for the opposition, that can be turned around in too short a period. You look at Donegal, if they go six or seven points up the game is over.
"It might be something we have to address. We are very attack-conscious, we have some massive runners from our half-back line, even corner-back with Keith (Higgins), it's probably something that when get into those positions, we make sure we not taper ourselves completely, but make sure we don't lose a seven-point lead inside 10 minutes.
"Even in games we've won, the Cork game, after my goal this year we conceded a goal straight away and put ourselves under pressure, Donnacha (O'Connor)'s goal, we were up by maybe five or six points at the time.
"The Kerry game in Croke Park, we were up by five or six and let it slip, so absolutely you can't be putting yourself in that position and expect to be playing 100 miles per hour football because if we're playing all-out attack all the time, we're going to be leaving gaps at the back and we've been exploited too many times."
O'Shea also described recently-appointed captain Higgins as "Mayo's best footballer of all time, in my opinion". He explained: "Keith's obviously a three-time All Star in a row now and probably one of the most consistent players in the country now and our most decorated footballer. He probably changed his attitude under Horan as well. He's probably taking football more seriously than he ever has."