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

Yes, Chapter 33 provides two distinct examples of Udi curing sleep problems, as noted by R. Hari Sitaram Dixit. In the first case, a friend of Dixit's had been unable to sleep for eight days despite taking a doctor's medicine. After Dixit gave him some Udi, the friend reported sleeping very well that night. The second instance involved a child from Bandra who had not been able to sleep for two months. His father took him for Sai Baba's Darshan in Shirdi, and the child was able to sleep soundly that very night and every night thereafter.