In a bowl, beat together the butter, brown sugar, white sugar, vanilla, peanut butter and eggs. In a separate bowl, mix the flour, bran, oats, and baking soda. Stir the flour mixture into the butter mixture until smooth. Drop by rounded teaspoons onto an ungreased cookie sheet.
Bake for 15 to 18 minutes in the preheated oven. Remove to a rack to cool.