According to The Sun UK, Messi explained in an interview with Argentine actor Mingo that this summers events on and off the pitch had got the better of him - and the hair was just part of a new start.
He explained: "I made a change to start from zero.
"A lot had gone on, things had happened, and I said to myself: “I have to break this and start again'”.
The Copa America defeat was particularly tough for Messi to take - and his brief retirement was seemingly due to his own sense of feeling like he'd failed.
He continued: "It was how I felt in that moment. Everything came crashing down.
"I felt like that [final] was the one, given how the team was and how we’d played in the competition. It was a huge disappointment.”
Messi will look to guide Barcelona to a defence of their La Liga crown this season and attempt to wrestle the Champions League off Real Madrid.
It will be recalled that the Argentinian superstar had announced his retirement from international football after Argentina's penalty defeat to Chile in the Copa America.
But he returned this week and in typical fashion scored the winner against Uruguay to announce his comeback in style.