Why did Sai Baba sleep with lit lamps around him when he was on the suspended plank?

The source material explains that when Maharaj (Sai Baba) would sleep on the wooden plank he had hung from the rafters, he would place four lit lamps at the four corners. As chapter 0 details this peculiar arrangement, it also notes the plank was suspended by old rags that seemed too weak to hold it. While the text describes the presence of the lamps as a fact of how he slept, it does not provide an explicit reason for why he kept them lit. It is presented as part of the mysterious and miraculous circumstances surrounding his sleeping on the plank.