Can you explain the miracle of Sai Baba's sleeping plank as described in Chapter 10?

Chapter 10 describes the seemingly impossible feat of Sai Baba sleeping on a very narrow wooden plank. This plank was only four cubits long and a mere one span wide, hung from the rafters with old rags. The chapter notes that lamps would burn at His head and feet while He slept. What made this miraculous was not just the precarious setup, but that His movements—when He got on or off the plank—were completely imperceptible to anyone. As stated in Chapter 10, the plank itself was merely for name's sake, as it was His great Siddhis, or divine powers, that made this possible.