What allows the external conflicts to become internal?

The setting of the novel is one big nightmare. So, yes Winston's external conflict with the Party consumes him internally. Winston's world is a dystopia of the highest order. There is no freedom, no joy or any real emotion at all. Winston looks and feels like hell. Orwell allows us into Winston's head where all his external conflicts have manifested inside of him. Winston's internal struggle is profoundly intellectual as much as it is suffocating. All the drudgery that Winston takes in externally is processed internally.