the consequences of long-term ear defenders (and sunglasses) are comparable to those of painkillers; you get used to being under their effect and your body assumes this as the new norm.
once this desentisation has happened, you will have lost your primary means of blocking out input (light, sound, headackes...), so you must transfer to something stronger to get an actual effect.
i myself do always carry ear defenders and sunglasses, but i limit their use to a minimum, to prevent just that; and i am already noticing the effects still.
mainly while driving; i put on the sunglasses there as a precaution, but more and more often, i need them at night too (LED streetlights and sharp-blue headlights...) which is resulting in me being effectively blind without them during the day. i'm trying to reverse the effect by driving in sunlight without glasses, but that is dangerous at the moment...