According to Ayurveda, it is said that one should avoid eating it at night because it aggravates cough and cold. It takes a long time to digest and makes one feel lazy too.
Given that IgE-mediated food allergy is generally considered to be dependent on the proteins in the food, it may be possible that there is change in the banana proteins with over-ripening, perhaps similar to cooking proteins in tuna or potatoes, that alters the immunogenicity of the banana protein.