Hormone therapy can cause exaggerated emotions. For some people, that can be bursting in to tears unexpectedly, or bursting out laughing inappropriately (in my case), or losing your temper when you wouldn't have expected to, etc.
Understanding this is important, but also trying to keep control of it for the sake of yourself and others around you. You might benefit from relaxation classes and exercise classes. Check with your hospital cancer care centre [Macmillan?] to see if they offer these, and also check with a local prostate cancer (or general cancer) support group - often these classes are available cheaply or for free for cancer patients. It's not just the classes themselves which help, but also meeting and talking with other patients in the same situation - that's just as important. Obviously, be careful during the chemo, but also use it as an opportunity to talk with other patients - that can be one of the best therapies. Destressing and exercise also help with sleeping.