In a medium bowl, cream together butter and sugars. Beat in eggs one at a time, then stir in vanilla. Combine flour, soda, salt, and cinnamon; stir into the creamed mixture. Mix in oats. Cover, and chill dough for at least one hour.
Preheat the oven to 190 degrees C (375 degrees F). Grease baking trays. Roll the dough into 2 cm balls, and place 4 cm apart on cookie sheets. Flatten each cookie with a large fork dipped in sugar.
Bake for 8 to 10 minutes in preheated oven. Allow cookies to cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely.