Long-term study not only affects students' psychological and physical wellbeing but can also affect their sex lives, even leading to impotence in males, according to a German study.
Its author, Manfred Kuba, a psychologist from the University of Gottingen, runs an advice centre for students.
About 60 per cent of long-term students seeking help at the centre are men.
The study found they were "disproportionally prone to impotence and relationship problems" compared with students who completed their courses on time.
"The feelings of shame that long-term students suffer often lead to a sense of isolation and even a complete withdrawal from society," Professor Kuba said.
His colleague Hermann Staats, a doctor at the advice centre, added: "If someone fails to meet the demands made on them, then of course it affects how they live and, just as important, it affects their love lives. Those affected are under enormous pressure, so it is no wonder this shows in their inability to perform sexually."
About 3,000 students use the centre's services each year. The researchers found long-term study causes not only sexual problems but problems with relationships in general. Student couples argue more when one partner has successfully completed their studies and the other is still struggling, the study shows.
In Germany, anyone who takes more than the set 14 semesters (there are two a year) to finish their degree is considered a long-term student. Although women are not exempt from long-term study stress, they are better equipped at dealing with it than men, the study shows.
"It is more acceptable for a woman to break off her studies than for a man, especially if they have a solid reason such as starting a family," Dr Staats said.