Twenty-one-year-old Hart is rated as one of England's best goalkeepers - but he has lost the number one jersey at Eastlands after the club signed Shay Given.
Hart has now been dropped to the bench and Hughes admits that the youngster needs to be playing regular first-team football.
"Joe knows our feelings with regard to his ability," Hughes told the News of the World.
"He is going to be England's outstanding goalkeeper for the next 10 or 15 years.
"Maybe just training day after day is not what he needs."