I've heard Udi can help with sleep issues. Are there any examples of this in Chapter 33?

Yes, a footnote in Chapter 33 provides two distinct examples of Udi curing sleep problems. The first story is about a friend of R. Hari Sitaram Dixit who had been unable to sleep for eight days, even with a doctor's medicine. Mr. Dixit gave him some of Baba's Udi, and the very next day, the friend reported that he had slept soundly all night after taking it. The second example involves a friend's child who had not been able to sleep for two months. The father took the child to Shirdi for Sai Baba's Darshan, and on that very night, the child got sleep and continued to sleep well every night thereafter.