I've been having a lot of trouble sleeping. Does the text mention if Udi can help with sleep issues?

Yes, the footnotes in Chapter 33 of the Shri Sai Satcharita provide two specific examples of Udi helping with sleeplessness. In one instance, a friend of R. Hari Sitaram Dixit complained of being unable to sleep for eight days despite taking a doctor's medicine. Dixit gave him Sai Baba's Udi and instructed him to take it for three days. The very next day, the friend reported that he had slept very well throughout the night after taking the Udi. A second story in the same chapter mentions a friend's child from Bandra who had not been able to sleep for two months. After being taken to Shirdi for Sai Baba's Darshan, the child slept soundly that very night and continued to do so thereafter.