Thanks for the support and comment @foxof. Elephant do sleep standing up, as do horses, The female in the photo was still lying in exactly the same position when we came back past her about an hour and a half later. She must have sensed us as she got up just after we went past her. I have sat and watched elephant sleeping on the same side for hours on a number of different occasions. The website you linked to appears to have been written by some one who is going on the old rumours. It does not sound as though there is any 1st hand experience there.