Online methods of working demanded by today's students have increased lecturers' workloads, according to a survey.
Lecturers' union Natfhe found that unrealistic student expectations forced lecturers to develop their own online learning facilities, often without support.
The 532 respondents to the survey, published on Friday, report pros and cons of teaching online. They say the lack of recognition of its implications is a worry.
One respondent complains: "Students believe you should be online seven days a week and 24 hours a day. It is quite normal for them to email you on Sunday demanding to know why you haven't answered their email or commented on their discussion forum contribution, posted late on Saturday evening."
Another says: "Students started sending extended chunks of writing by email. I included a requirement that chunks of writing must come by hard copy. This stopped students sending ill-planned first drafts as soon as they had finished writing them and has led to more thoughtful work."
Overall, 87 per cent of respondents, the majority of which are in higher education, say they use some form of online learning with their students.
Most of those not online say they do not know enough about it, although some are more hostile. "I do not get paid enough to spend time doing this.
It is not in my interests as once everything is online the university does not need me any more," one lecturer writes.
Liz Allen, who conducted the survey for Natfhe, said pressure from students had intensified and boundaries for their expectations needed to be set in a different way. In addition, many lecturers were keen to develop online facilities but lacked the technical expertise.
In some cases, online learning seemed to consist of little more than providing students with web-based resources while continuing to teach them in the same ways. This was not only laborious but lacked any pedagogic or time-saving benefits, Ms Allen added.
She said that although respondents had revealed the patchy development of online learning, a more systematic introduction held the danger that some lecturers might feel it was imposing an unwelcome uniformity on their teaching.
Those respondents who are more positive say the student experience is enhanced by online learning, that they are doing their job better and that, once expectations have been managed, they are able to deal with students more effectively.
In addition, the greater diversity of delivery methods and resources caters for a greater diversity of students, especially those who find attendance difficult. Most respondents say the value of online learning is when it complements face to face and other traditional methods.