How did Sai Baba sleep, and what was so mysterious about it?

According to Chapter 10 of the Shri Sai Satcharitra, Sai Baba's sleeping arrangement was highly unusual and mysterious. He would sleep on a narrow wooden plank, merely one span (about 9 inches) wide and four cubits long, which was suspended from the ceiling rafters with rags like a swing. What made this truly mysterious was that his movements were imperceptible; no one ever saw when he climbed onto the plank or when he descended from it. The text suggests this was not a normal physical feat but a display of his great Siddhis (powers), making the plank's structural support 'merely for name’s sake'.