The documentary film "Invisible" follows various bulgarian heroin users throughout their day. There are many other documentaries like this, namely "Black Tar Heroin", but this one turned out to be especially interesting to me because instead of highlighting what their Drug of Choice does to them, it focused on what were their perspectives about happiness, life and how they saw the world. The documentary can be watched with english subtitles in the link below:

https://www.youtube.com/user/tarabas4o/videos