“The Vianney's, who were devout Catholics, went to distant farms to hear Mass, celebrated clandestinely by loyal priests who risked their lives to bring the sacraments to their flocks. Jean-Marie’s instruction for his First Communion had to be carried out in secret by two laicized nuns. The ceremony itself took place in 1799 in a private house at Ecully. While Mass was being celebrated, the windows of the drawing room were shuttered so that the light of the candles could not be seen.
…
“He slept only two hours each night, rising shortly after midnight, going to the church where he remained kneeling without support until it was time for him to say Mass.
“His sleep was frequently interrupted by the devil who assaulted him with deafening noises, insults, and physical attacks, and once even setting his bed on fire. But Satan himself admitted that the Blessed Virgin Mary protected the holy priest, and he was powerless over her.
“Many witnessed these diabolical visitations, but the Curé of Ars accepted them as a matter of course and often joked about them.”
https://thecatholictravelguide.com/destinations/france/france-ars-sur-formans-shrine-st-john-vianney/