Preheat oven to 350°F. Grease a 12-cup cupcake pan, or line with paper liners.
In a large bowl, sift together the flour, cinnamon, baking soda and salt, then whisk in the hemp, flax and chia seeds.
In the bowl of a stand mixer fitted with the paddle attachment, beat the bananas, both sugars, oil and eggs. Add the flour mixture to the banana mixture in two additions, beating until blended after each addition.
Divide the batter among the wells of the prepared pan and sprinkle each muffin generously with 1 teaspoon of hemp hearts. Bake until golden brown and a toothpick inserted into the center comes out clean, 18 to 20 minutes. Transfer the pan to a wire rack and cool completely.