Over two decades, a quiet revolution has been taking place on third-level campuses all over the country, a revolution that parents who went to college in the Sixties and early Seventies may find surprising.

It's a revolution, indeed, that means students are unlikely to start a revolution - they'd never have the time. Deirdre, a Dublin mother of a teenager who left home to go to college last autumn, is one who didn't realise that going to college nowadays is a bit like going to work: it's a four-and-a-half or five-day week, then a quick hop on to a bus that whisks you home every weekend.

Deirdre had psyched herself up for her eldest daughter's departure for a college far from Dublin; she prepared herself for the trauma of missing her firstborn. But she didn't have time to: four days after she'd gone, her daughter was back. And she has come home every weekend since.

Suggestions that she might be missing out on the experience of going away to college by coming home are met with incomprehension - not to mention injured cries of "most people's mothers want them to come home!" Everybody, her daughter told her, goes home at the weekend.

And for once, it turns out that everybody does exactly that. Victor Connerty, associate dean of UCD's faculty of arts, understands Deirdre's surprise at student life in the Nineties: himself a Cambridge graduate, he says, "We were brought up to think of university as a whole experience." (Indeed at Cambridge, in his time, students had to get permission to leave the city.)

No more. A ring around colleges and RTCs all over the State confirms that student life now takes place between Monday morning and Friday lunchtime. That's when fleets of private buses start massing on the edge of every campus to pick up thousands of students homeward bound.

Fridays used to be the big night out for students of the Sixties, and there was usually lots to do at the weekends. Now, Thursday is the night to howl. There are still sports events at the weekend, but other college societies have to cram their activities into a four-day week, and all major student social events take place on Thursday evenings.

Reports that colleges have to cancel lectures on Friday afternoons don't find widespread confirmation, but it seems accepted that attendance at Friday-afternoon and (to a lesser extent) Monday-morning lectures are badly affected by the mass exodus.

Students' union presidents Dermot Lohan (DCU) and John Nesbitt (UCD) agree: many students lead two lives, one at home and one at college.

"They're going home to be with their friends and family, maybe to a job they have there; it does change a bit after first year, as some move away from friends at home and start to enjoy the city's weekend culture," Nesbitt says. "But it's very hard to break into Dublin social life unless you have a good circle of friends in college."

Nesbitt himself is a Dubliner, but Lohan hails from Athlone and still goes home frequently, though he's in third year. He stays up if there are USI events to attend to, but he still commutes regularly.

He's not likely, however, to run into many Athlone RTC students when he's at home; like other RTCs, it pretty much closes on Friday afternoon. One parent of an Athlone graduate remembers that every Friday for three years she drove to Maam Cross to pick up her daughter from the "`Lilac Bus".

Why do students do this? The simplest answer seems to be because they can. Carmel O'Sullivan, UCD's dean of women students, remembers that when she came to UCD first in 1972, Saturday night was still the big night out; however, in the midSeventies, a growing number of private bus operators got licences, and by the 1980s the bus business took off.

Now students can travel to and from the most remote parts of Ireland every weekend for a maximum of £8 return. PAMBO, an organisation representing private bus operators, says perhaps as much as onethird of their business comes from transporting third-level students at weekends. A company like Nestor's, which plies the Dublin-Galway route, doubles its fleet of six buses to 12 at the weekend.

Another Factor is the number of landladies who will only offer five-day digs. Many families like this, of course, because it costs less. And everyone agrees that going home for the weekend - for a proper feed, to get the washing done, and to raid the larder for bits and pieces for the week ahead - saves money too.

O'Sullivan reckons college life has changed considerably. "It's a question of participating. Students depend more on their home environment for their social life and for extracurricular activities."

UCD's student population is divided about half and half, urban and rural, and the two sides tend to stay divided - so the pattern of country students travelling home every weekend tends to persist right through a student's college career.

In many RTCs, most students are from out of town, and most of these go home. This means that even students who would like to stay can't really do so because it is too lonely.

Pauline Staunton, student counsellor at Galway RTC, says staff would like students to get more involved in college life. They are advised that involvement in student activities will give them the edge in job interviews - "but they don't really seem to listen". Many just don't have the time to join societies, between lectures and going home.

O'Sullivan, Staunton and Dennis MacDonald, acting officer of residences and student activities at UCC, all look back wistfully on their own student years and think students of the Sixties and Seventies had more fun. MacDonald maintains that UCC still has a very lively, friendly college life, even if the trend toward commuting has started to affect it: for the first time this year, the Philosophical Society, the biggest on campus, moved its debates from Saturday to Monday nights.

The student of the Nineties is a different kind of person, of course, and it's a moot point whether they enjoy student life more, less - or just differently. Many just accept that it is the norm to have two lives, two sets of friends, often a job at home.

"They're not leaving home," is how John Nesbitt describes it. "They're just going to college."