Problems when sleeping in the train

Do you have any problems when sleeping on the train? Well, oversleeping is one of the common troubles I hear a lot, but on last Saturday, I slapped a man's belongings that was on his lap by an accident... I was standing holding a strap, but I was exhausted after playing table tennis. After a while, I was getting sleepy and eventually, I fell asleep while standing on the train. When the train shook, my hand slipped off accidentally and that was how I whacked his bag hard... Not to mention it, the man was really surprised, as well as I was, since I didn't realize I was sleeping. Although I apologized him for what I had done, he didn't seem to understand what had happened just a while ago. Yet, from this accident, I made up my mind not to sleep while standing on a train...