Sometime in June, 2015, or, maybe May, I restarted the practice of Transcendental Meditation aka TM. This method was founded by Maharishi Mahesh Yogi. I first underwent training in this method sometime in 1984-5 and even took the advanced TM Siddhi course also back in 1984-5.
After a lapse of so many years, one night (May or June, 2015) while lying down in bed, the original mantra came back to me spontaneously - calmed my mind and helped me sleep. From that night on, sleep has been easy with TM. Even during the course of the day, the mantra arises whenever there is worry, fear or tension. So far, it seems to work better for me at calming the mind as compared to other forms of meditation.
This is because, the mind needs an anchor (focus) in order to slow down. Otherwise, it goes on and on from one anxious thought to another.
I find it works even if there is no initial focus. The mantra auto repeats itself in the background, like a catchy tune which you just can't get out of your mind. The mind then automatically latches on to it without effort - it seems to like the calm that comes from the mantra. A natural tendency of the mind to be drawn to the source of greater satisfaction.