I do occasionally have problems sleeping when I travel and I usually take drugs (diphenhydramine - the antihistamine sold as Benadryl in the US, over the counter, but Ambien if I really need to)
I assume that my issues are just I'm getting older and sleep is harder anyway, and my routine is different from home. I'm not drinking as much water, I'm eating different food (maybe at different times - jet lag never used to bother me, but once I hit 40, it does? And for a long time....) The biggest thing that helps me is moisture - consistently trying to up my water intake (at home I drink a gallon a day, so if I get half that when traveling, it's a good day...) and moisturizer for my skin.....
I thought EU had outlawed smoking in bars & restaurants? I haven't had a problem in my European travels in a long time.....