Third shift is an intriguing beast. What I say here is naturally in regards to my own experiences with such work, but I imagine that most of it can be extended to other workplaces. I won't bore you with the specifics of my present career, suffice it to say there are lots of scary sounding chemicals, large and expensive machinery, and lots of scary yellow lights that make blue things look black.
Rather, I would like to address third shift and the effect it has on employee motivation. While this will not be true everywhere, third shift can be quite dull. A lack of higher-ups to create work which needs doing leads to, well, a lack of work which needs doing. At my job, I moved from second shift, which was arguably the busiest at this particular business, to thirds. When, all of a sudden, there is comparatively little to be done, you can easily find yourself filling time through mindless busywork or less. This is very habit forming. I would say that during a slow night, I spend upwards of half my shift searching for things to do and, when that fails, browsing the net (which is consequently what lead me to E2, but that is neither here nor now). Since this is the rule and not the exception, when a busy night comes around, you are no more inclined to put in a hard day's night than on a slow night. And so, work does not get done.
Lack of work begets lack of motivation. Lack of motivation begets lack of work. It's a vicious cycle.