I agree with you, that when we feel depressed we begin to ask these philosophical questions of meaning. It's like being trapped in a dark room, which makes you make a judgment of the world outside your room from your position and situation in the dark room. However, I think asking the question of the meaning of life is important to examine by your own thought process what life is. You can read many books, but eventually you will come to your own conclusion with your own convictions.