Preheat oven to 350 F.
In a bowl, combine bran, flour, sugar, cinnamon, baking powder, baking soda, salt, and apples.
Add sweet potatoes, egg, egg whites, oil, and yogurt. Stir all ingredients thoroughly. Spray muffin tins with vegetable oil spray and spoon 1/4 cup of batter per muffin.
Bake for 20-25 minutes. Enjoy!