I wrote about this in my topic "Spiritual Senses" somewhere in this misc topic forum.
It's a very common sense that reopens to those entering a spiritual lifestyle, especially when they are accepting of it. Some are frightened by it and deny the gift.
Using the spiritual senses we have is the best way to increase its strength. I found that by accepting that we can see/hear/feel energy and focusing on what we sense is the absolute best way to put the thought consciously in our minds "hey, I like this and want it to sharpen". Like a muscle, we must exercise it in order for it strengthen and become more precise. I never recommend forcefully opening such senses with ritual or chakra manipulation. This could open you up too fast and cause you to not be prepared for it. This can become overwhelming and even frightening! Which can very well make you deny the gift and then you're further back then square one. By allowing it to develop naturally, you not only learn HOW to use it and understand it, but you also slowly become adjusted to its presence in your everyday life. It isn't a light switch that you can turn on and off at will. Once its activated it's there all the time. And once you deny it, it become ten times harder to get it back.