Bergeron, who has nine goals and six assists in 21 playoff games, appeared to be shaken up after coming to a stop behind the net in the second period Saturday's contest against the Chicago Blackhawks, although there was no contact on the play.
He skated to the bench under his own power and remained there for a short time before leaving for the dressing room.
The Bruins said he had been "taken to a local hospital in Chicago for observation," and Sunday announced he had been released and has rejoined the team.
No reason for the hospitalization or any details of a possible injury were given.
The Bruins fell to Chicago 3-1 Saturday to go down 3-games-to-2 in the series, and now face elimination as the Stanley Cup Finals head back to Boston for Monday's Game 6.