Generic, Text: Meta: the Stun game mechanics

Stunned characters suffer a penalty of -1d to skill and attribute rolls for the rest of the round and for the next round. A stun no longer penalizes a character after the second round, but it is still "affecting" him for half an hour unless the character rests for one minute.

 

If a character is being "affected" from a number of stuns equal to the number before the "D" for the character's Strength, the character is knocked unconscious for 2D minutes. A character making an Easy first aid total can revive an unconscious character.

— "Damage" rules summary on D6 Holocron, with emphasis added for quick reference. Thanks, D6 Holocron!