When it comes to the Health Benefits that we can get from bananas, we know it is coming both from bananas and banana peels; the amount of nutrients depends upon the qualities of bananas, on the level of how ripe it is. It's found that the less ripened, green peels of bananas are more effective in curing digestion issues. In contrast, the much-ripened banana peels strengthen the white blood cells to face and fight infections and disease.
Note - these tests and research were done on rats and not on humans, and therefore it is yet to be ascertained whether the banana peels are effective on humans or not.

There are various other reasons were banana peels are found super helpful and effective; the reasons are stated below -

The presence of tryptophan in bananas along with B6 in the banana peels helps one who is prey to depression and other things triggering moods. This happens when tryptophan turns into serotonin after breaking down; this helps to elevate a better mood.
Since both banana and banana peels are highly composed of Vitamin A, it plays a significantly influential role in improving eyesight.
Being really rich in fiber, bananas help in the easy digestion of food.