30 Rock star Tracy Morgan's publicist has revealed the actor suffered from a combination of exhaustion and altitude when he collapsed at the Sundance Film Festival in the US.

Lewis Kay said Tracy is grateful to the Park City Medical Centre for its care after he collapsed on Sunday. Park City's elevation is 7,000 feet (2,133 metres).

Tracy was escorted from the Creative Coalition Spotlight Awards ceremony.

His publicist said hospital officials report no drugs or alcohol were found in Tracy's system.

Source: Press Release