Nothing makes sense except in the light of origin (more true than biology) and that is why we see the legends of origin everywhere without any exception, folk stories, religions, philosophy and science. Although we hear the claims that it is just in modern time that we have become anthropocentric, but humans were always anthropocentric as they couldn't have any external brains to borrow for their thinking and understanding. It is just the subjects of interests have changed over time. If I make it personal then I can only trace my origin to my childhood (that is as far my memory can take me) and that is where to look back to make sense of everything. The first time, I heard about about sixth sense was from a sufi lecture mystifying it with all those breathing practices. I thought, let it go as it appears something external that comes from inside (hard to make sense of it as I hadn't it since my childhood). But from time to time, I feel (as all others express from time to time) that there things that you can't understand and instead you have to feel them. They might look stupid and you might look out of your senses but they are real. They look stupid because they are beyond common senses and have to be felt. Take for example, a poem that touches your heart. If you look at it, its verses might not be in proper order with no logical connections, but because it syncs with your feelings, you might feel great to read or when you might enjoy listening it. The social norms contain our emotions and since childhood we are reminded everyday, what is accepted expressions of emotions and what are not. That is why emotions are mostly pressed or least expressed part of us (you don't feel comfortable to express them). In other words we trade our originality to the accepted social norms (means we mostly fake ourselves in order just to look normal). The most funny part is that, despite we know it, still we try to press others by constantly reminding them to be in their senses (and so we could assure ourselves that we are good learners of social norms).
So, originally, we get five senses plus emotions that are ASAP contained by everyone around us. But there comes times, when we let these emotions free for brief moments and become truly emotional (brief moments of originality) and those are the moments that we really feel that the sixth sense is not something that comes by sufi practices or breathing exercises (As they appear to be something mythical and are just to impress others. If there was something as sixth sense that everyone should have experienced it somehow. As emotions are something common and looked upon as something dangerous that is needed to be contained, so naturally, it is one of the senses that we do not let to develop and use it). It is already in us and it needs an external force to give you enough courage so you could face, the social pressures of norms and become brave enough to be truly yourself even it is for brief moments. Now, I don't look to sufis for the sixth sense but to artists, poets, actors and writers whose whole work depends on emotions (sorry, 6th sense). These are the group of people who have more originality in others as they have learned it how to master their emotions partially rather than suppressing them.