I had read in Lonley Planet that there's a few points of etiquette to remember when travelling by trains in Ukraine.
One them is to remember to bring something appropriate to wear for sleeping and getting around the train of an evening. Essentially you have to bring some sleep togs. I shared my compartment to Odessa with Olga - a financial director of a medium sized firm in Odessa. She bustled in with someone who I thought to be her husband. He sized me up and gave me that: 'listen kid, if there's any funny business here I'll kill you look.' But my anxiety was put at ease when Olga broke out into English and said he was only a friend not her husband.
Stationary, the trains are very stuffy but once the train moves the air-conditioning kicks in. The conductors are decked out in a quasi air hostess uniform that does quite take off. Soon after departing they come around and offer tea in wonderful ornate glasses.
Olga told me about her work and come sleep time she gave me the nod to leave the compartment for her to change. I stepped outside into the corridor and nodded to other passengers doing the change to jim-jams swap routine.
When it came to my turn I was please that my Calvin Klein pj's and t-shirt combo did not raise any eyebrows.
And if you think you can sleep on a bumpy night train in Ukraine - forget it. My advice, take a couple of liberal shots of vodka to help you doze off.