Adrenaline Theory

From Ben10 Fanpedia

Maybe the hosts body unlocks the power code like when they produces adrenaline it unlocks the unlimited power so he can go alien like you would in bad situations. Then when he experiences serious amounts of pain it cancels out the adrenaline and he no long can stay hero, then why he is not using the Omnitrix for important things he reverts back because there is no adrenaline left.