From one of the three books floating around in my purse...

When a man is asleep, he has in a circle round him the chain of the hours, the sequence of the years, the order of the heavenly host. Instinctively, when he wakes, he looks to these, and in an instant reads off his own position on the earth's surface and the amount of time that has elapsed during his slumbers; but this ordered procession is apt to grow confused, and to break it's ranks. Suppose that, towards morning, after a night of insomnia, sleep descends upon him while he is reading, in quite a different position from that in which he normally goes to sleep, he has only to lift his arm to arrest the sun and turn it back in it's course, and, at the moment of waking, he will have no idea of the time, but will conclude that he has just gone to bed. Or suppose that he gets drowsy in some even more abnormal position; sitting in an arm-chair, say, after dinner: then the world will fall topsy-turvy from its orbit, the magic chair will carry him at full speed through time and space, and when he opens his eyes again he will imagine that he went to sleep months earlier, and in some far distant country. But for me it was enough if, in my own bed, my sleep was so heavy as completely to relax my consciousness; for then I lost all sense of the place in which I had gone to sleep, and when I awoke at midnight, not knowing where I was, I could not be sure at first who I was; I had only the most rudimentary sense of existence, such as may lurk and flicker in the depths of an animal's consciousness; I was more destitute of human qualities than the cave-dweller; but then the memory, not yet of the place in which I was, but of various other places where I had lived, and might now very possibly be, would come like a rope let down from heaven to draw me up out of the abyss of not-being, from which I could never have escaped by myself: in a flash I would traverse and surmount centuries of civilization, and out of a half-visualized succession of oil-lamps, followed by shirts with turned down collars, would put together by degrees the component parts of my ego.

Marcel Proust, Swann's Way.