India, June 5 -- I don't know about you, but this happens to me all the time. I will be sitting on the couch, watching a show, and suddenly feel that my eyes are shutting of their own accord. I shake myself awake and tell myself I must make it to the end of the episode. But it's no use. I drop off to sleep again.

So, I turn the TV off and make my way to bed, all bleary-eyed and sleepy, turn off the lights and lay my head on my pillow. And then, suddenly, I find myself wide awake. All my sleep seems to have vanished in the short distance between the den and the bedroom, and now no matter how hard I try, I simply cannot drop off.

What mysterious alchemy is this? Is this a uniquely me thing or does it happen to everyone? As I lie awake, wi...