Research by Sue Wallace of Nottingham Trent University at three colleges in Lincolnshire and Nottingham found that a lack of jobs was demotivating students and affecting their classroom behaviour.
She said that continued pressure on college finances, leading to rising class sizes and less individual attention, was also contributing to disengaged students with little motivation.
"There are so many young people who don't believe that their educational careers will lead to meaningful employment," said Dr Wallace. "We don't have enough data yet, but it does seem that the places where employment was lowest the problem of motivation was highest."
The research involved staff in lesson observations, starting last year, noting incidents of poor behaviour, as well as the strategies lecturers used to counter it and how effective they were. Lecturers were also interviewed about their experiences in dealing with bad behaviour.
Dr Wallace said: "What we wanted to know was what were the most common learner behaviours that promoted barriers to learning. We also wanted to find out the strategies teachers found most effective."
She said the problems experienced by lecturers were the same across very different vocational areas, from beauty therapy to construction: lack of punctuality, failure to complete work, and talking over their teacher.
"It does seem to be about lack of motivation, not about `bad behaviour.' One of the ways we can address that is by making them feel valued and respected. It's more about the pastoral role in FE than about pedagogy," she said.
But she said cost pressures meant students were taught in increasingly large groups and often learning alone on computers which made pastoral support more difficult.