From what I can remember trains leave Giza, in Cairo about 6pm to arrive in Luxor overnight about 6am the following day. Sleepers can be booked but it is possible, done it, to travel 2nd class, sit next to an inspector, and sleep in your seat. First class is waste of money. Return at about 8pm overnight to Cairo following morning. Cost about E£50.00 if my memory serves me right.($15.00) See free site at
http://community.webshots.com/user/geds12121 for several hundred photos of Egypt with commentary.
Have a good time, enshallah.