The newspaper said the wide receiver-kick returner has struggled with the problem since he was 10 years old.
"I got a little light-headed during (Sunday's 27-24 win over San Francisco)," he told the newspaper Thursday. "(I) was a little drowsy, got a little tired at times, but like I said, I try not to let that affect me."
The former University of Florida product, a first-round pick by the Vikings in the 2009 NFL Draft, is the first player in franchise history to score a touchdown in each of his first three games.
Harvin leads the Vikings with two touchdowns on 12 receptions for 128 yards, and he scored Sunday on a 101-yard kickoff return.